Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Classic Telescopes

Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | (show all)
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Inspecting a C8 Prior to Purchase
      #5048967 - 01/31/12 10:58 PM

Please could anyone offer advice on inspecting a 1970s vintage Celestron C8 orange tube prior to purchase? The current owner wants $500 for it and a 12.5" Newtonian home-built. I suspect it may be possible to buy just the C8 for about half that. I have heard that the mirrors are likely to be good on a Cat despite the age, because they are protected inside the sealed tube. It looks clean in the photographs I have seen (sorry I can't post them just now; my laptop can not resize them). Are there any common defects I should be careful to avoid? It is complete, but I suspect the motor does not work on the polar axis.

I'm thinking of the C8 as a muscular heft-and-go scope, manageable if a few pounds beyond grab-and-go. Is it quick to set up? Am I likely to be happy with it as a general purpose scope? Planets, DSOs -- I'd use it for everything. It would be the biggest scope in my collection and my first cat.

Gotta love those triangular, spring-steel legs!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Grava T
Pooh-Bah
*****

Reged: 06/18/08

Loc: Quebec, Canada
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5048983 - 01/31/12 11:08 PM

Relatively quick to set up but a little long for cool down. Depending on the conditions I would think a good hour before med-high power eyepieces could be used with great success....but for a general purpose scope, it is awesome. I used mine a lot without the wedge in alt/az mode. Very comfortable to use and one can view seated all night long.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Grava T]
      #5048999 - 01/31/12 11:17 PM

Thanks! I'm not worried about cool-down time, because I'll store it in the barn.

I love that something so old could be so good. I like feeling as though I'm using what I might have used had I pursued astronomy at a younger age, when it first appealed but I was doing other things.

Other opinions?


Post Extras: Print Post   Remind Me!   Notify Moderator  
greju
Carpal Tunnel
*****

Reged: 10/13/05

Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5049036 - 01/31/12 11:45 PM

Make sure the focuser turns smoothly and there is not excessive mirror shift. Also make sure you are buying it for the right reason. Because it is a classic-not for it's optics.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: Inspecting a C8 Prior to Purchase new [Re: greju]
      #5049090 - 02/01/12 12:35 AM

Look at secondary reflection in mirror and also look from rear port. Should be nice and clean. Depending on age, it could be a sandcast (holes in forks) or ribbed. Check that the RA lock knob securely locks and that you can easily and smoothly turn it a full 360 with the lock knob released via the RA slow motion knob. It should feel smooth all the way around. (If the RA Lock knob is to the right of the RA Slow Motion, then you have an older style that presses against the gear teeth instead of the version that pushed down on the flat metal side of the gear. I had one of these develop metal fatigue and it does not have the gripping force of the newer style. The newer style uses either a metal or nylon plate under the screw to push against the gear side, the metal can warp and loose grip, the nylon replaced it in the late 70's/80's and is better.)

Check that the Dec lock works and holds tightly. With it locked, the dec slow motion should be checked to make sure it can travel smoothly from one limit to the other. If there is excessive play or a little in/out motion on the dec slow mo knob, that may be adjusted out. If the Dec lock does not hold tightly, it may be adjusted by rotating the locking clamp. There may be a locking nut(s) present as well. These often can be adjusted so the knob remains operating in a normal vertical up/down position.

When plugged in, look at the motors on the bottom. In the little windows, you should see the motors spin.
Check that the RA setting circle can be smoothly turned all the way around. There should be some resistance/roughness as it is designed to move with the base (It is held there by a very large spring clip), and the knobs allow you to adjust it to the correct position, after which it should stay moving with the inner mount parts when turning in RA.
See if there is an indicator on the outside of the mount base that points at the RA circle. If not, then a little pencil mark or piece of tape can be applied and then set the setting circle so that an even hour is at the line. Make sure the RA clamp is locked, and let it run for 10-15 minutes. You should see that the circle has moved that far from the point you set it. That and the motors spinning will tell you if it is tracking ok if you can't do a full star test/setup on a wedge.

As mentioned, run the focus both directions and note if there are rough spots. This could mean that it needs to be lubed, but sometimes just repeated full travels will help spread the grease. (If it needs to be lubed, you can do this, there are lots of instructions on taking the corrector and primary out and relubing the primary shaft and focus threaded shaft.) If it grinds, I would be concerned.
Expect 20-40 full turns, depending on the style of the focuser threaded shaft. (The older ones have short stubby knobs above a large bearing holder, while the newer ones had a variety of thin knobs (<1") above a smaller bearing holder, sometimes the bearing holder had a large bottom rim to fit the older larger bearing hole.)

Check rough collimation, looking from the front of the scope about 8-10' away, you should see all the optics form concentric circles, if you don't then something may be way off.

If it has an orange plastic cover over the secondary, pop it off to see the serial number plate/collimation screws (little screwdriver will do it) If it has a serial number plate on the secondary, this normally should be straight level when viewing the scope with the tube level and the forks straight on to you. If it is way out it is possible someone removed the corrector and didn't return it right or the secondary mount was loose at some point. (C was putting them out level, but can't guarantee that 100%)
If it is a metal secondary holder that is smooth with a central screw and 3 outer collimation screws, you can't check this easily.
Don't even think of trying a flashlight test!
There may be dust present inside as well as outside the corrector, as long as it is not excessive.
Any dust or marks external of the corrector may be cleaned up following the proper cleaning methods. (Search about cleaning.)
Do see if you can do a star test, allow the scope to cool for an hour, as thermal issues will not allow a good test.
Check the images just inside/outside of focus, looking for the bullseye pattern. This should be noticeable and when centered, should be concentric. There may be differences in how it looks inside/outside of focus, but you don't want to see it lopsided and flip orientation when going through focus, as that is astigmatism I believe. (For full optical tests, see Suiter or Piekiel's books.)

If the power cord is not present, one can be obtained. If the plug is on the side of the base, then a Cinch Jones 2 pin receptacle is needed (Mouser Electronics). If it plugs in on the bottom of the base by the visible motors, then you can use an HP style plug. We can help you locate a cable/parts if needed. If you don't have power, you can't test the motors.

Hope this helps,
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
gnowellsct
Postmaster
*****

Reged: 06/24/09

Re: Inspecting a C8 Prior to Purchase new [Re: Brian Risley]
      #5049130 - 02/01/12 01:09 AM

For an old c8 and a 12.5" it's a steal just get both and sort it out later.

The inner mechanism is easy to disassemble and you can clean and lube that baffle with some synethetic grease like slick 50 bearing grease or mobile 1 bearing grease.

http://www.astromart.com/articles/article.asp?article_id=594

for disassembly of the c8


Post Extras: Print Post   Remind Me!   Notify Moderator  
Napersky
Carpal Tunnel
*****

Reged: 01/27/10

Loc: Chicagoland
Re: Inspecting a C8 Prior to Purchase new [Re: gnowellsct]
      #5049420 - 02/01/12 08:56 AM

While I can't help you with your question I concur with GravT Michael that it is a great scope. I love my C8 and it is really a kind of mini superscope.

I believe that the American SCT: Celestron, Meade was perhaps the greatest contribution to Amateur astronomy by
American engineering and manufacturing (past) as I don't count the Tascos, Unitrons, as domestics.

The huge aperature, the control of the fork mount, tracking, what I can do with the SCT I can't do with my Refractors...at least I don't think I can.

Mark


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: gnowellsct]
      #5049558 - 02/01/12 10:32 AM

Quote:

For an old c8 and a 12.5" it's a steal just get both and sort it out later.




I'm glad you said that! That's what I'd do.

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: greju]
      #5049638 - 02/01/12 11:19 AM

Thanks, Everyone;

I will check every last element of your detailed suggestions. Such thorough lists! It's always wonderful to have so much help available. Amazing how the Internet has changed an arcane hobby into an international community. My grandfather was a farm boy who became a great aircraft mechanic. He spanned the Wright Brothers to the Space Shuttle. Our times are no different!

There is quite a range of opinions about this old C8, mostly favorable, such as:

Quote:

for a general purpose scope, it is awesome.




But, there are also some cautions. Greju suggests:

Quote:

Make sure... there is not excessive mirror shift.




I've never really understood "mirror shift," because I've never had a SCT of my own. If I follow, the scope focuses by moving the primary mirror, so any imperfection in the mechanicals means that the image may pan somewhat when focusing. At high magnifications, bad image shift could pan my object out of view. Is that correct?

Quote:

Also make sure you are buying it for the right reason. Because it is a classic-not for it's optics.




This is a wonderful comment to find among all the enthusiasm for old C8s. I am fascinated with old scopes. I love the idea that I can develop my skills on gear that is more primitive than the current standard, believing the extra challenge teaches better skills. I also like the feeling of catching up on life, of doing decades later what I might have done when I was younger, yet while using the same equipment. I'm pretty sure this is the scope I saw this scope advertised in comic books and "Boy's Life" magazine when I was a kid. (Yeah; comic books -- inexpensive advertising when test marketing back in the day.) Having a piece of history appeals to me. Those are good reasons to buy a classic.

Moving on to questionable motives: How happy, or disappointed, am I likely to be with my allegedly practical reasons for the purchase?

A new C5 would cost about $500; a new C8, $1,000. Suppose I could buy this vintage C8 for about $250 with the wedge and glorious spring-steel tripod, maybe $300. It would have much more aperture than the new C5 and same as the new C8, yet inferior coatings and less reflective mirrors, and perhaps crankier mechanicals. Is this the low-cost ticket into the world of large aperture, reasonably easily transportable scopes? I confess to be seeking a low-cost workhorse as I continue to learn the skies. I don't mind a few quirks and a little less brightness, so long as it frees me to see far beyond my 60mm refractor and 4" reflector. I do worry about the lessened contrast from the large central obstruction when viewing planets, but not too much, so long as it will show me distant galaxies and star clusters. Would an old C8 fit the bill, or do I need a reality check and more time to save my nickles for a newer scope?

Yeah, I admit -- I'm hoping an old scope in good condition will help me to see the skies well beyond my budget for newer gear. Am I delusional?

And, assuming the scope is in good condition, at what price would I become an overpaying Romantic fool?

Edited by Joe Cepleur (02/01/12 11:47 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Geo.
Carpal Tunnel
*****

Reged: 10/01/08

Loc: Upstate NY
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5049794 - 02/01/12 12:49 PM

Right on image shift. Panning is a god way to express it. There's about 1/1000" clearance between the baffle tube and the primary carrier. This is less than your average auto engine rod bearing. But if the grease isn't distributed evenly the clearance is enough to let the carrier pivot or "pan" on the baffle tube during focusing. Bad shift will pan the object right out of the FOV!

Only a few orange Super C8s were StarBright, so the coatings of this C8 will be either standard Al SiO2 on the mirrors and perhaps antirefective on the corrector ("Special Coatings"). Starbright is noticably brighter than the standard coatings. So the light thruput of an orange C8 is about the same as a C6 XLT.

If you are disappointed the current market of an orange C8 kit is about $500. You've got nothing to lose.

BTW, if there is a gray haze on the inside of the corrector, don't worry it cleans right off.


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: Geo.]
      #5049838 - 02/01/12 01:20 PM

An old orange tube C-8 is no slouch. I think the chances that the optics might be excellent are better with an early one, who's optics might have been hand-figured, versus a new one cranked out in China on some machine. The new ones are probably more consistent, but probably not as good as an outstanding old one.

Question is, are you getting one of the better ones? And the answer is, if you're getting a C-8 AND a 12.5" Newt for $500, it doesn't matter! You can recover your investment in the unlikely event you've got a dog. Maybe keep the Newt and sell the C-8.

I think an old C-8 in good condition should be worth between about $300-500, depending also on accessories.

I got lucky last October. I found one on the Las Vegas craigslist that was on my way to Utah, for $250. Be sure to scroll down on this thread to where I imaged Jupiter with it. It turns out it's probably the best SCT I've ever owned. I had a ~1980 orange tube that was almost as good optically, but I sold that to a friend a couple years ago.

1975 Orange Tube C-8 thread


Post Extras: Print Post   Remind Me!   Notify Moderator  
wfj
Pooh-Bah
*****

Reged: 01/10/08

Loc: California, Santa Cruz County
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5049984 - 02/01/12 02:52 PM

Lately I've been using my 80's "Orange Tube" C8 ("Special Coatings") as a table top alt-az. Plop it down on a picnic table or wood stool and use it with a short stool.

After collimating it with a barlow and a 5mm, and finding a weak zone at the 30% radius and undetectable SA via secondary breakout - it does quite well on Mars(406x) and Jupiter (6mm 338x) when well cooled.

For me with SCT's the make/break point is collimating and star-testing on Polaris - if you have such an accommodating seller. If it collimates and you can measure accurately the breakout of the secondary shadow inside/outside focus to a fraction of a turn, it passes my "good enough" test.

I have some excellent 4" refractors and maks, but I still see more detail (seeing & cooling permitting) with SCTs than them. Newts do better same aperture or bigger, but they are heavier/bulkier.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5050315 - 02/01/12 06:18 PM

Quote:

An old orange tube C-8 is no slouch...

1975 Orange Tube C-8 thread




No slouch, but apparently not as easy to set up as I had hoped. Or, was it just a bit of a bear to prepare for astrophotography? For visual work, I typically toss a scope on the ground with a fair approximation to a polar alignment, and then just tweak the dec axis along with the polar axis as the image drifts. If that were your standard for the C8, would it be quick to set up?

Seeing the going prices for C8s, I should grab this puppy while I can. The 12.5" Newt sold with it is a homebuilt, no idea if it's built with an old shaving mirror or a fine Cave, but the mount looks good in pictures. If I could only store the thing and it were good, it might be the featured scope in an observatory someday.


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5050412 - 02/01/12 07:24 PM

For visual, you don't need to go to great lengths to polar align. You could set it up on the wedge and point it to 90 degrees declination (the pole) and move it around in azimuth until you see polaris in the finder.

Setting up the way you describe would take a minute or two at most, and would be fine for visual. I really consider the orange tube C-8 a grab and go. I need to take mine off the tripod to get it in my workshop door, but if you have a wide enough doorway it's easy enough to move the whole scope by carrying it.

It's somewhat of a hassle to set up for deep sky astrophotography, but the setup for visual is usually fine for planetary imaging - just tweak the dec and RA controls to keep centered.

The Newt sounds interesting. A big Newt can take up a lot of room, though. But at the price for the pair, I would still encourage you to buy both and sell one to pay off the investment in the other.

I can't remember if I asked: Do you have pictures of the scopes?

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
davidmcgo
Pooh-Bah
*****

Reged: 10/09/04

Loc: San Diego, CA
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5050682 - 02/01/12 10:09 PM

For visual I sometimes use mine in alt az mode with the drive base set on a tall barstool, and me on a low chair and just use the slow motions to track. A right angle finder helps in that mode.

Tim, I can't wait to see how your repaint of old #135 turns out. Glad mine was a smooth finish vice the velvetone.

Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: davidmcgo]
      #5051196 - 02/02/12 08:28 AM Attachment (95 downloads)

Got pix from the seller. Been iced into my road for several days. Never know whether a seller is bluffing or honest about alleged other buyers.

I am hesitant to resell a scope at a profit, because I trust the original source who notified me of the scopes. The seller is selling not just her scopes, but her heart to a good home. It would be good business, but bad karma, to profit from the purchase. She adds that the 12.5" Newt has not been used in one year per inch of aperture.

Edited by Joe Cepleur (02/02/12 11:52 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051197 - 02/02/12 08:29 AM Attachment (77 downloads)

Mirror cell...

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051199 - 02/02/12 08:30 AM Attachment (66 downloads)

Home-made focuser?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051200 - 02/02/12 08:31 AM Attachment (73 downloads)

Anyone recognize this mount? Looks as though it would clean up well.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051201 - 02/02/12 08:31 AM Attachment (60 downloads)

Another of the mount...

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051205 - 02/02/12 08:32 AM Attachment (73 downloads)

Did I mention a C8?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051207 - 02/02/12 08:34 AM Attachment (58 downloads)

Maybe not a bad purchase for a Romantic Classicist whose astronomic aspirations outclass his budget...

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051210 - 02/02/12 08:35 AM Attachment (59 downloads)

and who prefers grab-and-go to schlep and heft...

Edited by Joe Cepleur (02/02/12 08:35 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051211 - 02/02/12 08:36 AM Attachment (48 downloads)

Eyepiece case available separately.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051212 - 02/02/12 08:37 AM Attachment (44 downloads)

Volcano tops! Kelners, okay; of historic interest...

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051217 - 02/02/12 08:38 AM Attachment (45 downloads)

An Ortho and a Brandon! Hhmmm; tasty...

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051219 - 02/02/12 08:40 AM Attachment (47 downloads)

Further evidence of home-building of the Newt: an ocular made from likely a Kelner (?) from an old binocular.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051221 - 02/02/12 08:41 AM Attachment (45 downloads)

And another view:

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051235 - 02/02/12 08:49 AM

Okay! Now that I've posted my first images to Cloudy Nights, I really owe it to you all to post images of the classics already in my collection (or, "crowding my house," as the case may be). I don't suppose anyone would care to see the Fecker Celestar 6 hiding at my club?!

So, anyway; whaddaya all think of the C8 and the 12.5" Newt? The C8 could be come my workhorse. Er... could the C8 become my workhorse? The vote seems to be "yes," so long as it proved to be in reasonably good condition beyond the pretty pictures.

Can't imagine what I would do with the big Newt until I had a place of my own to house it. All the worse given the hassle of testing it and storing it... or, are you die-hard scope rescuers saying a mirror that size could be refigured, and the mount looks promising, so...

Yeah, I know. If I learned to refigure the mirror myself, which I would love to do in another, more settled life, there is no end to what one might see in a big, equatorial Newt. Could even upgrade the focuser!

By the way, it's not as though I'm short on projects. My interest in the C8 is partly historic, and partly to corral a workhorse for everyday use now, as I have said. But, already on the table after the kind efforts of my club's optician and machinist is the 4" refractor mentioned in my signature, a legacy from our club's late founder. It's at a prototype stage where it needs to be used and studied to determine how to finish the objective. So, in deference to the favor already done to me, and with the desire to see that scope completed, I already need to learn to grind glass, let alone start another big project.

I hear ya thinkin'... when I have my own observatory someday... 12.5 inches...

Edited by Joe Cepleur (02/02/12 08:55 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5051799 - 02/02/12 02:11 PM

Do you have a garage where you can store the Newt on industrial casters? That way, you could roll it out onto the driveway fully assembled. I do this with my scopes, and it reduces setup time to a few minutes at most! And when I used to keep my 12.5" Cass in my garage, I had a spot on the driveway where I could set it up and be accurately polar aligned right from the start. We have tenants in the apartment over the garage now, though, and I don't like waking them up opening my noisy garage doors!

I seem to recognize the mount, but I can't place it. It might be a limited production commercial mount, or a well-executed homebuilt. Restored, that Newt could be worth a K or two. Helical focusers are nice, particularly for accurate visual focusing. That might be a commercial unit, though I don't recognize it.

If the primary's coatings are bad, OWL still has a 50% off deal on recoating services. I've got three 8" mirrors due back today from him. He coated my 10" f/6 a couple years ago and did a nice job. Unless the primary was a bad one, it shouldn't need refiguring. You could probably clean it and try it out on the stars and verify its quality before sending it off for a recoat (versus refiguring).

I hear you regarding not profiting off these old classics. I prefer selling things at prices comparable to what I paid for them. Or, if I've put a lot of work into them, a reasonable compensation for the work I've done, or the value of the completed scope, whichever is less. I feel best when I don't profit off my friends.

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5051932 - 02/02/12 03:23 PM

I like the idea of rolling a scope out of a garage or shed almost better than building an observatory. Rather than being contained within walls, one is truly outside under the stars. Where I am living now, I need an easily portable scope, or binoculars --maybe a vintage C8-- something for running around the yard dodging the trees, or to be taken easily to another site.

I had no idea that that hulk of a Newt might be worth a grand or two when restored. Might be worth storing for quite a while until it had a home. A scope like that could easily be the last scope a visual astronomer could ever need. Twelve-and-a-half inches of equatorially mounted Newt is serious by any measure. Kind of a joke for a guy who is pinching pennies just now (one reason for a *vintage* C8!), but looking forward, that Newt could be the centerpiece of a fabulous visual observatory someday. Are you saying that, at the price it is offered, the bones are there, and the optics could be fixed if necessary, so I need not worry whether it is a dog in its current condition?


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5052010 - 02/02/12 04:12 PM

Yep, that's what I'm saying!

Post Extras: Print Post   Remind Me!   Notify Moderator  
wfj
Pooh-Bah
*****

Reged: 01/10/08

Loc: California, Santa Cruz County
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5052051 - 02/02/12 04:35 PM

A very reasonable deal. If you can make it work, suggest you do, because you're likely not to get much better.

C8 is a nice scope all around. The 12.5 has double the area, and can make quite a difference in what you can enjoy.

You can also make a dob base, or acquire one from other sources, if you find the mount a bear. What I did to eval a legacy scope like this, was to incline the scope on the railings of a deck on Polaris, and did a star test.

I found my motivations for any scope sale changed considerably with a good star test. This was confirmed when my skeptical son went "Whoa!" at spotting a galaxy off M13 when I got it home and setup on another mount - it was a similar scope.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: wfj]
      #5055165 - 02/04/12 01:34 PM

This story is not yet finished, but is progressing nicely. Tomorrow, I expect to see the C8 in person and buy it.

Even better, like a good binary star, my angst over the absurdity of my buying the 12.5" Newt is resolving. In our club is a man who is studying to become a professional astronomer. Last fall, he was looking to buy a big mirror to build a scope for his observatory under dark skies. Looks like he'll buy the big Newt. I'm embarrassed to admit I did not think of him myself; I wish I'd suggested it to him. He has all the skills to fix it perfectly, better than new (and better than me!), and I'll be able to drop by his place to observe with it!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5055621 - 02/04/12 06:57 PM

Update: I just spoke with the seller, who got in touch with the man who sold her the scopes some years ago. Lady Cepleur and I shall be meeting her tomorrow.

The 12.5" Newtonian is an old Parks. My friend will buy it, and put the cell and mirror into a new truss tube atop the Atlas mount in his observatory.

The C8 will cost me $250 complete with the tube, mount, tripod, trunk, eyepieces, and original bill of sale from 1976. The motor does not work. Anyone know how I would fix it, or where I could send it for repair?

Edited by Joe Cepleur (02/04/12 08:52 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5055636 - 02/04/12 07:11 PM

I don't remember parks ever making a mount like that. It looks too nice to be parks

Post Extras: Print Post   Remind Me!   Notify Moderator  
Ira
Carpal Tunnel
*****

Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5055643 - 02/04/12 07:14 PM

It looks like an Astrola mount for the Newt. I would just defork the C8 and put it on a nice alt-az mount. Problems solved.

/Ira


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: Ira]
      #5055654 - 02/04/12 07:22 PM

Not an astrola either. Parks bought the cave patterns, so their mounts look a lot like the old caves. This mount is either a limited production mount for astrophotography, or a well executed design by an amateur machinist.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5055659 - 02/04/12 07:25 PM

Update: I just spoke with the seller, who got in touch with the man who sold her the scopes some years ago. Lady Cepleur and I shall be meeting her tomorrow.

The 12.5" Newtonian is an old Parks. My friend will buy it, and put the cell and mirror into a new truss tube atop the Atlas mount in his observatory.

The C8 will cost me $250 complete with the tube, mount, tripod, trunk, eyepieces, and the original bill of sale from 1976. The motor does not work. Anyone know how I would fix it, or where I could send it for repair?


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5055660 - 02/04/12 07:25 PM

There are no nice altaz mounts!

If you deform the c8, make sure to loose. The bolts holding one of the fork arms to the base, or you'll scratch the tube.

-Tim


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5055784 - 02/04/12 08:47 PM

Boy, that iphone post! I meant to say if you deforK the c8, make sure to loosen the bolts holding one of the fork arms to the base, or you'll scratch the tube.

Also, if you defork it, keep the mount! When you're done with the scope, pass it on to another classic collector.

...but the fork mount makes a decent altaz mount itself, if you use it without the wedge. I just prefer tracking myself.

When you get it, make sure it really does or doesn't work. The drive is very quiet and only rotates once/day, so a novice might think it's not working if they don't watch it long enough.

Replacement motors shouldn't be too hard to find for this scope, assuming you need them.

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: tim53]
      #5055820 - 02/04/12 09:07 PM

Wouldn't it be funny if the C8's motor always worked, and the poor seller did not know it! She preferred the manual controls to lugging batteries and inverters. (Honestly, what were the engineers thinking when inventing AC drive motors?!) The seller is clearly knowledgeable of the sky, but admits to having little technical knowledge of her equipment.

I'm not surprised that the original owner of the Newt could not recall the manufacturer. He has not seen the scope in over a dozen years. I suspect a home-built cobbled together from some pretty good parts, but I'm happy to be wrong. Whatever the mount, it looks good to me. In my club, we have fine optics on pipe mounts!

More news tomorrow after I see the scopes and try a daylight star test with the reflection of the Sun off a Christmas tree bulb. First light report tomorrow or the day after, if the skies are clear tomorrow night.

Why are folks suggesting removing the C8 from its fork mount? Isn't the joy of finding a classic being able to use it in its original state? Or is there a problem with these old fork mounts?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ham Radio
professor emeritus
*****

Reged: 09/18/09

Loc: Baxter, Mn
Re: Inspecting a C8 Prior to Purchase new [Re: Joe Cepleur]
      #5056337 - 02/05/12 07:36 AM

Hi Joe, I have a 1977 C-8 and I love it just the way it is. It works great, and when I take the time to get it aligned properly, it tracks very well. It seems to be very stable and as long as I remember to not bump the thing, there is very little vibration when I am focusing.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Ira
Carpal Tunnel
*****

Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: Inspecting a C8 Prior to Purchase new [Re: Ham Radio]
      #5056468 - 02/05/12 09:17 AM

No need to defork unless the old fork mount isn't working right. I just prefer using my old C8 on a modern alt-az mount, a T-Rex.

/Ira


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5057781 - 02/06/12 12:51 AM

I bought the C8, serial number 284077, and am heartened by the many stories of burned-out hulks being restored to fine service. Remember the thread about the shreds of a Cave Astrola found in a field by the restorer's wife while she was riding her horse? This situation is not so bad, not nearly, even if the scope is not yet ready for use.

The seller's house was in a dense forest, so it was not possible to test the focus on any distant object. As it was mid-day, there were no stars, nor was there a Moon overhead. I managed to kinda-sorta focus on the branches of trees, but they were too close to be clear. They were also confusing. With the narrow depth of field, it was not possible to focus on an entire twig at once. I was edgy about buying something I could not properly test. Recalling the admonitions from this thread that nearly any C8 was worth buying for $250, and hearing the same on the phone from a skilled astronomer friend, I bought it. So... chump or victor? Which am I?

The mirrors are in pretty good shape, not pristine, but I've seen far worse in scopes yielding good images. There is a little dirt inside, and a few small areas may be peeling. Having been used at the seacoast for many years, the scope has deposits of salt inside and out. In a pleasant surprise, the scope is stickered as having "Special Coatings" (anti-reflective coatings on the corrector plate).

Upon arriving home, the scope was tested with a known good 32mm Meade Series 4000 Plossl. I believe --I hope!-- it is badly miscollimated. Nothing comes to properly clear focus. the Moon looks fuzzy, as though its craters were covered with white mold. Stars are never pinpoints, but only faint, fuzzy dots. Lady Cepleur notes that looking at the image with her eye off-center to the eyepiece improves overall sharpness greatly. I've never collimated an SCT before, but I get the idea: During a star test, play with the three Allen screws positioning the secondary until the diffraction rings and Airy disk are aligned. (Can anyone advise of a better way? I know to replace the Allen screws with collimating knobs from Bob's Knobs.)

There is a list of I hope Not Big Deals: One of the spur gears on the polar axis drive is damaged. The heads are broken off the thumb screws holding the finder, so they'll need to removed and replaced to fix the alignment. The finder's cross hairs are damaged. The diagonal may need tweaking or replacing to eliminate a slight wobble. The bolts holding the tripod to the wedge and the wedge to the mount are just whatever the seller had on hand. The focuser works, but its knob is missing; one must turn the axle instead.

Worst of all for me, the declination axis has a fine adjuster, but there is no slow motion control on the polar axis. Should there be, or does this scope rely solely on its electric motor for tracking? I hope not. Perhaps there is an aftermarket solution allowing manual tracking? And, can the dead AC motors be replaced with DC? Can the drive be upgraded to worm gears?

What is this fascination I have with old things? Partly it's my wanting a scope that I must work myself, not one with a computer-controlled mount. It's a statement; I will learn the skies, and will not let some mount fool me into believing I know more than I truly do. Partly it's the feeling that an old object helps me to catch up on life, as though using something I might have had in my youth atones for lost time. Partly it's pleasure and sanity in defying the consumer culture's belief that one must always have the newest to have the best. Whatever my motives, I'd rather restore this scope than buy a new one. On this forum, everyone understands. I'll post more pictures and we'll get to work on the fixes. Thank you all for your help.


Post Extras: Print Post   Remind Me!   Notify Moderator  
ccw
journeyman


Reged: 02/01/12

Loc: Sydney, Australia
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5057858 - 02/06/12 03:12 AM

Hi all, I am newish to astronomy, have always had an interest since a kid with my Tasco special and look around for an upgrade long story short I now own a nice C8.

I purchased a C8 Serial No. 813272 from ebay and I am very happy with it. I may have payed a little to much for it but with the amount of joy i get out of using the scope I don't mind. The Scope came in very good condition. The paint is in very good condition only a few minor scratches (i think i added more scratches then was orignaly on it when mounting it to the fork v_v )

Can anyone give me detail about the history of my scope from the Serial No eg date of manufacture?

Joe: I know exactly what you mean about driving the scope yourself. I am having great joy in learning and star hoping. Frustrating at time but rewarding the same.

I am trying to keep the scope as original as possible with upgrades that are only bolt on or removable.

I am also trying to use this scope for astrophotography with mixed results. Main issue is I have a 80's(?) 9V DC fork mount and no wedge so tracking as a bit of a problem, otherwise pic of the moon are great.

Now with aperture fever, I'm looking out for a good c14 orange tube to add to my collection If anyone know of one for sell at a good price please let me know (but i do live in Australia)

Sorry to carry on and maybe in the wrong place, just glad to see other getting the same enjoyment as I am out of a C8

ccw


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: ccw]
      #5057925 - 02/06/12 06:30 AM

Welcome, CCW! You've very much in the right place announcing yourself here as one with an interest in fixing and using C8s. Maybe you'll be the one to say something important about fixing mine, or someone else's, that no one else has said. For now, that joy you mention can be tinged with trepidation while awaiting seeing how well a newly purchased classic may succeed in being repaired. Thanks for reminding me why we do it!

For astrophotography, are you aware that wedges are often sold separately on Cloudy Nights classifieds, eBay, or Astromart?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059171 - 02/06/12 08:11 PM Attachment (53 downloads)

I am greatly looking forward fixing this classic and hope the following photographs will help.

The scope was used for many years immediately on the Atlantic Coast. Salt from the air coated all surfaces inside and out. This wiped off of large surfaces, collected in crevices, and may have corroded the motors. The dirt is from a worse source. Rather than dismount the scope from the wedge properly to transport it, the former owners routinely unscrewed the single bolt holding the motor housing together. The housing was thus often opened to the air, and so it is now filled with dirt. Note the broken spur gears. Careless handling would have contributed to the broken gears.

Where would I get new gears and motors? And, are there DC replacements, or must the new motors be AC like the originals?


Edited by Joe Cepleur (02/06/12 11:49 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059175 - 02/06/12 08:13 PM Attachment (41 downloads)

The underside of the top half of the mount. (The fork attaches on the opposite side.) The large gear has a few bad teeth, and is missing a screw. Is this this gear driven by the motor, the slow motion knob, or both?

Edited by Joe Cepleur (02/06/12 10:49 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059181 - 02/06/12 08:17 PM Attachment (33 downloads)

Note the gap between the setting circle and the motor housing. This is the result of loosening the single bolt holding the housing together. Is it meant to serve as the fork's axis, or was this an accidental axis used only after the motors froze?

Edited by Joe Cepleur (02/06/12 10:53 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059186 - 02/06/12 08:18 PM Attachment (28 downloads)

The underside of the wedge. The three bolts holding the motor housing are not correct. Anyone know the correct size? Something custom for this mount, or something standard? It looks as though the heads would turn, so they could slip through the slots for quick release of the scope from the wedge.

Edited by Joe Cepleur (02/06/12 10:59 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059187 - 02/06/12 08:19 PM Attachment (36 downloads)

The heads to the finder's thumb screws are all broken. Is there any way to remove them short of having a machinist drill them out? Not shown: The finder's crosshairs are broken. Can the be repaired or replaced?

Edited by Joe Cepleur (02/06/12 11:01 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059189 - 02/06/12 08:20 PM Attachment (42 downloads)

Big news! The secondary's support is loose! It wiggles nearly a millimeter at the slightest shake, and rotates freely. The collimation is clearly hopeless until this is fixed, likely explaining all of why the scope will not focus in its current state. Nice to have a solution to the most important problem!

The Allen screw holding the obstruction to the corrector is frozen. Any ideas about how to free it? Worse comes to worse, could I use penetrating oil? Gotta clean the optics anyway, and am afraid of damaging the corrector with too much force.

The Schmidt corrector and mirrors are covered with salt. The buyer of the big Newt and I have already planned a four-handed mirror-cleaning party to clean his and mine!

Edited by Joe Cepleur (02/06/12 11:12 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059190 - 02/06/12 08:21 PM Attachment (42 downloads)

Different lighting of the previous view. I tried to light the tube from the inside, so far without success. In person, one would see the salt inside the scope, along with dirt on the mirrors. A C8 is not sealed and nitrogen purged like a good binocular, so the salt would have worked its way in over the years. The dirt has simpler origins; the prior owners never covered the diagonal after removing the ocular for storage. Some of the blemishes may be peeling coatings rather than dirt. I will likely leave them as is after cleaning and just see how well the scope performs, rather than throw money at recoatings. It needn't be showroom new if it drives well.

One important exception: Can anyone attest to how much reflectivity the original coatings would have lost in thirty-five years? How much better might the scope be with new coatings? If the images of the restored scope are good, might I be losing so much light as to render my C8 effectively a C6? If so, I'd send those mirrors off to Optic Wave Laboratories for recoating immediately, before the Dow hits 14,000, ending their 50% off sale!

Edited by Joe Cepleur (02/06/12 11:25 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059194 - 02/06/12 08:21 PM Attachment (33 downloads)

I have the knob to replace the bolt capping one of the two ends of the declination axis. (There should be a knob at each end.) The hole on the base at the right needs a new slow motion knob and gear for the polar axis. Anyone know where to get them?

Edited by Joe Cepleur (02/06/12 11:30 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059199 - 02/06/12 08:22 PM Attachment (30 downloads)

The star diagonal is a bit floppy. It may be okay, or I may be able to tighten it, or it could be replaced. Where do I buy the knob to cover the focuser's axle? It's a special, long, hollow knob, to cover and protect the focuser's threaded post from damage as it slides in and out of the scope.

Edited by Joe Cepleur (02/06/12 11:35 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059202 - 02/06/12 08:23 PM Attachment (24 downloads)

Where do I buy the proper bolts to hold the wedge to the tripod? It looks as though they should have rotating heads to slip through those long openings for quick release.

Edited by Joe Cepleur (02/06/12 11:38 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059203 - 02/06/12 08:23 PM Attachment (34 downloads)

A good example of the salt coating all crevices. It looks awful, but should wash away easily. Interesting to see what extended coastal use does to a scope.

Edited by Joe Cepleur (02/06/12 11:41 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059204 - 02/06/12 08:24 PM Attachment (31 downloads)

The charcoal grey goo reinforcing the black diagonal evidently tightened the ocular holder so it would not rotate downward under its own weight. This scope must have had a lot of use to have had need for such modifications. If only it could tell stories!

Edited by Joe Cepleur (02/07/12 07:51 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059556 - 02/07/12 12:11 AM

Looking back on the purchase from the perspective of all I've learned in a day of tearing the scope apart, I can see how I might have negotiated a better deal with the seller. $250 bought the complete C8 (optical tube, fork mount, wedge, and tripod), and also some Celestron oculars of the same vintage, along with some accessories in a foam lined, plastic storage case:

40mm Kelner
25mm Kelner
12mm Ortho
16mm Brandon

Homemade Kelner (?) from the right eye of a binocular (rotates for fine focus)
Porro erecting prism for terrestrial viewing
Two adjustable Barlow lenses (the lenses slide inside the tubes to adjust power)
Red filter
Tiny yellow filter (maybe fits inside a Barlow?!)
Counterweights (used to balance heavy oculars and cameras; where do they attach?)
Power cord
Storage trunk for OTA (serviceable, but needing to be repaired or replaced)

I paid $250 for the lot. What does that make me; chump or hustler? My gut tells me that I need to improve my negotiating skills; but, if things go right, after the scope is fixed, it may work well enough to be worth what I paid -- which it was not at the moment I bought it.

What do more experienced buyers feel the lot was worth?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059608 - 02/07/12 01:05 AM

Joe, Have you downloaded the 1975 manual for the C-5/C-8 from Company 7's Site. Later color manual here!

(This is an older manual, but does show the dec slow mo assembly very nicely.)

There is only one dec knob on the OT's. The other side is for adjusting it. Release the nut and adjust the pivot so it moves freely but does not move in/out, then tighten nut.

Measure the width of the focus knob needed with calipers.
There aren't any general supplies but you may find one at Astro Parts Outlet.

(In all honesty, once you get a chance to check the optics, I would ditch the fork and go GEM or pickup a used one that is in good shape. You will spend more looking for motors/gears. (The gears can be obtained from Boston Gear, but attaching them to a motor shift is a real PITA!) I have replaced the RA slow mo knob on one of mine, but I only needed the gear and shaft, had the knob.
The visible gear is for the motors only! There is another gear under the plate (held in place by the central 4 screws). The 3 outer screws keep the gears together. Don't remove them as there is also a large flat spring and the RA setting circle to deal with.
This is the only way to go in and replace the RA knob shaft!
When you do, you will find either a metal or nylon piece directly under the RA Lock screw. (Nylon is better!)
Motors are not off the shelf, they are 1 RPH Counter Clockwise and you would probably have to fit the correct gear on it. When doing that, it is very easy to damage the internal gearbox setup too!
(I completely rebuilt my 71/72 and have had my 80 apart, so I say this from experience!)

As for the optics, I would lookup one of the disassembly instruction sites and remove the corrector ring and look on the edge of the corrector for the serial number. (It should be on the side directly opposite the focuser! You will need to then remove the secondary (center screw holds the mirror in, tighten the 2 sections of the holder (it screws on to the corrector with the inner baffle. Once positioned, you can replace the secondary, look for a line across the back of the holder/mirror or on the side of the mirror. This line/mark should line up with the middle of the serial number on the corrector.
(The serial number is very hard to see, you may need a magnifying glass. Look for a mark on the side of the corrector, it should be there with the serial number.)
If you can't find a serial number, then it is possible that the corrector was broken and replaced with glass! That could explain a very fuzzy image!
Hopefully that is not the case!
They used to sell no tools knob sets for the tripod/wedge screws, but not sure if any are available now. You can purchase your own. The screws to hold the wedge threaded down into the tripod. Celestron used allen head screws for a long time. Many people replaced them with other screws that they could use with a wrench and not worry about the head size.
(I can probably disassemble that thing blindfolded, I did it enough with my older one when rebuilding it!)

I think Tim is starting to get that way working on his early one!

Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: Fixing a C8 After Purchase new [Re: Brian Risley]
      #5059611 - 02/07/12 01:09 AM

If it is the stackable counterweights (round with threaded shaft on one side, threaded hole on the other) you remove the screws located in the center top/bottom of the front cell. The 10-24 threads can then take the counterweights.
If it is a bar set, then the bar mounts on the front via the same hole and there will be 2 screws in the back to hold the support.
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: Fixing a C8 After Purchase new [Re: Brian Risley]
      #5059614 - 02/07/12 01:12 AM

The serial number is on the edge of the top side of the corrector, not on the thin edge. Think fine print size and possibly not easily seen straight on. Use a light at an angle.
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
sgorton99
Post Laureate
*****

Reged: 04/30/08

Loc: Wisconsin, Madison
Re: Fixing a C8 After Purchase new [Re: Brian Risley]
      #5059802 - 02/07/12 07:03 AM

Price wise I think you did fine. Can you post of pick of the EPs? The Brandon may go a ways toward that $250 total...

Steve


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: sgorton99]
      #5059864 - 02/07/12 08:09 AM

Quote:

Price wise I think you did fine. Can you post of pick of the EPs? The Brandon may go a ways toward that $250 total...




Woa! Sounds like I got lucky! I wanted the Brandon because the optician at our club always talks about them, but I've never seen one until now. Company Seven's Web site has a set of maybe five Brandons for about $1,000. Had no idea mine was that valuable!

There are pictures of all the oculars in the earlier pages of this thread.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Brian Risley]
      #5059888 - 02/07/12 08:29 AM

Thanks, Brian, for all the details about motors, gears, and knobs. Pictures would help. I'll download the manuals and look for a schematic, or perhaps find photos online.

It's probably good, practical advice to ditch the fork mount for a GEM, but the fork is original and exudes cachet. My club has a spare GEM, and I could use the original tripod, but might it also be possible to keep the fork mount, fix the R.A. slo-mo knob, and not bother with the motors? That would be fine for visual astronomy. One less battery to lug, and silent.

I don't follow about the R.A. axis's visible gear with three screws holding another, larger, hidden gear. The hidden gear works the manual slo-mo? You warn not to remove the visible gear, because of the setting circle's spring underneath. Will it be necessary to remove it anyway in order to fix the slo-mo?

Another possibility: Maybe the parts dealer would have a complete, functioning motor with housing, maybe even a Byers with worm gears.

Edited by Joe Cepleur (02/07/12 09:06 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5059988 - 02/07/12 09:50 AM

The inner ring held by 4 screws is safe to remove. That will allow the piece with both gears and the setting circles to be removed. (The outer 3 connect the 2 gear plates and sandwich the RA circle/spring.) The spring can be removed, it is just a big piece of spring steel that goes in and gives some resistance to the RA circle so it stays in place in relation to the gears unless you manually rotate it using the 4 black knobs on top.
I really recommend getting a new base if you want to keep the fork style. Some can be had pretty inexpensively. I picked one up for about $35 a while back. You can get the byers or even a later powerstar or celestar fork and use it. The c-8 holes for fork mounting have remained pretty consistent (don't know about the Nexstar/cpc holes).
The celestars could run off a 9v transistor battery, so you can be real portable and still have power.
I think trying to repair it would be more costly, especially if you do ever want it motorized.

To repair the RA knob, you need the gear, a pin and then a knob that can fit below the RA lock knob, so it has to be low profile. (It is basically the same size as the dec knob, but has a smaller shaft hole.)
If you do decide to go that route, I can look through my records for the pin/gear that I ordered (It's been 8 years, so I don't know if I still have the info, but I was keeping it stashed in a box). You still have to secure the gear to the pin, possibly some of the heavy duty loctite.
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5060039 - 02/07/12 10:22 AM

"Upon arriving home, the scope was tested with a known good 32mm Meade Series 4000 Plossl. I believe --I hope!-- it is badly miscollimated. Nothing comes to properly clear focus. the Moon looks fuzzy, as though its craters were covered with white mold. Stars are never pinpoints, but only faint, fuzzy dots."

Even in a bad collimated C-8, the image of a star will come to sharp focus, it won't be round, and will be coma shaped, but it will be sharp. The fuzzy dot appearance and fuzzy Moon sounds like a large amount of spherical aberration. The most likely cause is that the corrector has been flipped in the cell. The fact that the scope has a number of issues caused be the former owner and that the secondary cell is loose adds to the suspicion that corrector maybe backwards in it's cell.

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Brian Risley]
      #5060245 - 02/07/12 12:25 PM

Quote:

If it is the stackable counterweights (round with threaded shaft on one side, threaded hole on the other)...




I have those, thanks. I had not noticed that each had its own shaft and hole. All screwed together for storage, they look as though they are all mounted on a single, long shaft.

Quote:

you remove the screws located in the center top/bottom of the front cell. The 10-24 threads can then take the counterweights.




"Front cell," meaning the dark grey-brown metal casting holding the corrector to the orange tube? There are Allen screws top and bottom. Remove them, and screw the counterweights into the holes? I've been studying the manuals and will hope to find a picture.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: DAVIDG]
      #5060279 - 02/07/12 12:40 PM

Quote:

"Upon arriving home, the scope was tested with a known good 32mm Meade Series 4000 Plossl. I believe --I hope!-- it is badly miscollimated. Nothing comes to properly clear focus. the Moon looks fuzzy, as though its craters were covered with white mold. Stars are never pinpoints, but only faint, fuzzy dots."

Even in a bad collimated C-8, the image of a star will come to sharp focus, it won't be round, and will be coma shaped, but it will be sharp. The fuzzy dot appearance and fuzzy Moon sounds like a large amount of spherical aberration. The most likely cause is that the corrector has been flipped in the cell. The fact that the scope has a number of issues caused be the former owner and that the secondary cell is loose adds to the suspicion that corrector maybe backwards in it's cell.




Thanks! I had wondered whether the corrector might be in backwards, but only on intuition. How cool that the view matches what is actually to be expected. This also fits with one of the scope's oddities: The inside of the corrector is dirtier than the outside. Might guess the outside had been cleaned, except that the bigger dirt inside would have no better way to have gotten in there than to have been outside to start. The scope is so dirty that it clearly had lots of use, leading me to believe it will be good when we get it working. It may well have been cleaned somewhat, reassembled incorrectly, and then abandoned.

The manuals make a big deal of each corrector and secondary being hand-selected and perfectly aligned to 1/100th-wave. How am I going to put this back together correctly? The serial number on the corrector belongs in a specific location, but if a cat's whisker makes a difference, how will I align it? And what about the secondary? It's been flopping around for years. How do I determine which way to align it? Is there any easier means than star testing the scope between slight rotations of the corrector and secondary? How would I judge either's position if both the mirror and corrector had to be properly aligned for optimal result in a star test?

Is there any way to determine which side of the corrector faces out, other than to reassemble the scope and test it? Might the corrector's slight curvature result in any noticeable fun-house-mirror effect on the curved side? I believe only one side is curved, and it faces out?


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5060392 - 02/07/12 01:40 PM

I've refigured a couple of Celestron optics sets and I'm getting ready to do another on my early C-8 which has the tri-color paint and is serial #316.
If the optics don't have residue astgimatism it doesn't matter how the corrector or the secondary is rotated. You won't be able to see the curve in the corrector since it is not that deep. Sometime you can see were the gasket have left a mark and tell the front from the back that way. Also sometime the serial number is etched into the edge of the corrector face and that is usually on the face that points out. If you have a small optical flat, you place it around the 70% zone (ie 70% from the center) of the corrector and you'll see that the interference fringes have a good amount of curvature so that is the side that has the Schmidt curve and that side faces the sky. In any case, you'll see a big difference between having it in the wrong way vs the right way. The right way cancels the spherical aberration of the primary, the wrong way doubles it.
You want to center the corrector in the cell and then center the secondary holder using the ID of the corrector cell as a reference. Position the secondary cell so one of the alignment screws is at the 12:00 o'clock position. This makes it easier to figure out what screw to turn. Look up the rear port in the scope and by eye center the secondary by using the alignment screws. Now center a fairly bright star, Polaris works well since it doesn't move out of the field very quickly, slightly defocus the star so your inside of focus and center the black circle which is the shadow of the secondary in the center of the defocused star. You want to be on the inside of focus because the movement of the alignment screws will match the way you want the secondary to move. If your on the outside of focus the secondary moves in the opposite direction.
The fact that you have more dirt on the inside of the corrector then outside is another strong clue that the corrector is flipped.

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
greju
Carpal Tunnel
*****

Reged: 10/13/05

Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5060431 - 02/07/12 01:57 PM

Probably a little late but some good info.

http://www.scopereviews.com/C8History.html


Post Extras: Print Post   Remind Me!   Notify Moderator  
greju
Carpal Tunnel
*****

Reged: 10/13/05

Re: Fixing a C8 After Purchase new [Re: DAVIDG]
      #5060434 - 02/07/12 01:59 PM

"You want to center the corrector in the cell and then center the secondary holder using the ID of the corrector cell as a reference. Position the secondary cell so one of the alignment screws is at the 12:00 o'clock position."

I am not sure I have ever seen the alignment screws with one at the 12. Shouldn't they be in the same position as first assmbled or does that not matter?


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Fixing a C8 After Purchase new [Re: greju]
      #5060478 - 02/07/12 02:23 PM

It doesn't make any difference were the alignment screws are positioned, it just makes it much easier to match up which way the secondary needs to be adjusted with the position of the screws.

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: Fixing a C8 After Purchase new [Re: greju]
      #5060514 - 02/07/12 02:48 PM

There are alignment marks to get things back in proper orientation. With the old scopes, it is easy if you have a laser collimator to get the secondary holder centered, it has a central hole for the secondary. Once you find the corrector serial # and the marks on the back of the secondary, we can get things aligned the way they were at the factory. The shims are probably not present or not in their correct positions beside the corrector. We can make new ones.
I have only seen one bad C-8 set of optics. It was so bad, the corrector didn't even properly fit the cell! (Serial #'s matched on all optics!) It had a bad burnthrough radial spike problem. Not sure if it was corrector or primary that was bad.

Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: Brian Risley]
      #5060516 - 02/07/12 02:52 PM

Good! Alignment marks will make this manageable.

What material would be used to make shims? I'd like to have it on hand when I disassemble the scope for cleaning.


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Fixing a C8 After Purchase new [Re: Joe Cepleur]
      #5060699 - 02/07/12 04:49 PM

You can use 1/8" cork or gasket material as shim stock. What is critical is that you center the corrector using the OD of it to that of the ID of the cell, then center the secondary cell to the ID of the corrector cell. The reason is that when they core the correctors the hole may not be perfectly centered. In the factory they would core a stack of correctors together and some would not perfectly aligned. I have seen a number that were off by 1/8" or more. My C-5 is this way. If you center the corrector by using it's OD, it will then be optically as well as mechanically centered.
If you first center the secondary in the corrector then center the secondary holder, and the hole is not perfectly centered, the corrector will be optically off center. What will happen is that scope will look perfectly aligned but you'll get on axis coma and all the stars in the field will show coma pointing in one direction. Many people think it's the secondary being misaligned and will pull their hair out trying to get things right.

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase new [Re: DAVIDG]
      #5060870 - 02/07/12 06:23 PM

That story of off-centered holes in corrector plates is a revelation! Celestron advertised in its literature of the day that, although any combination of corrector, primary, and secondary would work well, they carefully selected, and aligned by hand, the best combinations for the finest possible results. I had not been able to understand how it would be possible to specially tweak spherical mirrors or radially uniform correctors. You're saying that, actually, the manufacturing process was sloppy at this stage, but they had a means to overcome its deficiencies?

Would it have been impossible to perfectly center all the holes? It may have made no difference during assembly at the factory, but think how much easier it might have been to reassemble the scopes after taking them apart for repair or cleaning.

A new question: Would there be any advantage to flocking the tube?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061841 - 02/08/12 10:11 AM Attachment (37 downloads)

Some things are wonderful when encrusted with salt: fresh pretzels from Pennsylvania Dutch country, smoked fish from the coast of Maine. Telescopes? Maybe not so good. I like 'em clean. I figured that Brandon was worth forty or fifty dollars when I bought the scope, and am please to have been misinformed. What is the real value? $150? More? Makes me feel pretty good having spent $250 on a scope that won't focus, yet I believe this tale may yet have a happy ending.

The greatest thread ever on Cloudy Nights Classic Forum read like a detective novel. Beginning with a name and address in the United States written on the case of an oddly fine, costly telescope manufactured in Paris, and continuing through public records of court cases, the story traced the scope's provenance to organized crime rigging horse races in the 1930s. The bookies would accept bets until just after a race was over, and then play a recording of its radio broadcast to the bettors that was just slightly delayed from real time. Knowing which horse had already won the race told the bookies which late bets to accept or reject, because an accomplice on the telephone would have already reported the results as he had seen them through the telescope. The current thread will not be quite that cool, but I may yet get my fifteen minutes of fame.

The following fourteen photographs, I promise, contain all the additional evidence necessary to deduce all relevant facts about the actual history of this particular C8: how it came to be encrusted in salt, and whether there is hope for its repair. To make it easier, the smoking gun will be present in the very first image. (Remember, the seller states that the scope was used for many years by the sea.)

Ready to play, super-sleuths?

When I wakened this morning and went to the window to see the sun rise over the frozen lake, I happened to look into the C8's tube and saw that the light was streaming into so as to finally allow a good photograph of the inside. A moment later, I saw the smoking gun. Can you see it? Like a deep space object, it is hidden in plain sight:

Edited by Joe Cepleur (02/08/12 01:00 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061842 - 02/08/12 10:12 AM Attachment (47 downloads)

With salt everywhere, there is an issue with the camera's depth of field. It is not possible for a close-up image to focus on both ends of the telescope at once, so this thread contains a series of not-quite duplicate images. The prior image focused on salt on the corrector. This one focuses on salt on the primary:

Edited by Joe Cepleur (02/08/12 12:53 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061843 - 02/08/12 10:13 AM Attachment (49 downloads)

Another view of salt on the corrector. The different angle emphasizes salt that was less easily visible before. Pretty cool how all those little salt-prisms glisten in sunlight, huh?

Edited by Joe Cepleur (02/08/12 12:53 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061845 - 02/08/12 10:13 AM Attachment (32 downloads)

Similar to the above, a different view of salt on the primary:

Edited by Joe Cepleur (02/08/12 12:54 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061847 - 02/08/12 10:14 AM Attachment (30 downloads)

The inside of the finder's ocular has tons of salt. More importantly, it has a damaged cross-hair. Hhmmm... No way it came damaged from Celestron's venerable factory in Torrance, California, of the 1970s. Did it damage itself? Poltergeists? For the record, the finder's objective and the inside of the its tube were clean.

Edited by Joe Cepleur (02/08/12 01:03 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061848 - 02/08/12 10:15 AM Attachment (25 downloads)

The diagonal is dirty, but oddly free of salt.

Edited by Joe Cepleur (02/08/12 12:55 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061849 - 02/08/12 10:15 AM Attachment (32 downloads)

Yeah; honest -- that's dirt, not salt:

Edited by Joe Cepleur (02/08/12 12:55 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061851 - 02/08/12 10:16 AM Attachment (41 downloads)

My precious eyepieces! Disgusting! Look at them, encrusted in salt!

Edited by Joe Cepleur (02/08/12 12:55 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061853 - 02/08/12 10:16 AM Attachment (24 downloads)

Okay, I hear ya thinkin' -- Dude, chill; there's a bit of dirt on the rubber eyecup of the one made from an old binocular; but, honest, those eyepieces are pristine! Maybe they need to be cleaned of some fingerprints and dust, but they're okay! Ain't no salt on 'em!

Edited by Joe Cepleur (02/08/12 01:05 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061855 - 02/08/12 10:17 AM Attachment (28 downloads)

Even the insides are clean...(!)

Edited by Joe Cepleur (02/08/12 12:56 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061857 - 02/08/12 10:18 AM Attachment (32 downloads)

You, in the back row! Stop screaming during the lecture! Oh, sorry; what's that? You want to see a close-up of the tiniest eyepiece?

Edited by Joe Cepleur (02/08/12 12:57 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061859 - 02/08/12 10:18 AM Attachment (21 downloads)

I've got all these great-big, shiny eyepieces, and all you care about is the tiny one that doesn't even say "Celestron" on it? Suit yourself....

Edited by Joe Cepleur (02/08/12 12:57 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061861 - 02/08/12 10:18 AM Attachment (41 downloads)

Digiscoping! Let's try digiscoping! I'm quite proud of this image and the next, as they required adjusting the camera's manual controls. Automatic mode could not get it. The C8's f/10 optical system made for too slow an exposure, so the system got confused between the dark tube and its bright objective end. Setting the ASA at 800, the shutter at 1/60 of a second, and the aperture to 5.6 nailed this image of the secondary. It's not clear to me whether its just dirty, or the mirror is peeling. Actually, I suspect it's peeling, but don't want to believe it. Any experts know for sure, or will the verdict await the scope's pending dis-assembly for cleaning? It may be useable as it. Hate to throw money at a costly recoating...

Edited by Joe Cepleur (02/08/12 12:58 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061864 - 02/08/12 10:19 AM Attachment (28 downloads)

Refocusing through the visual back shows the salt on the corrector, as seen from the inside:

Edited by Joe Cepleur (02/08/12 12:58 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5061974 - 02/08/12 11:12 AM

Now comes the spoiler alert. If you want to deduce how the scope came to be so encrusted in salt, pause at this post, because the next one reveals the answer. Hint: Although the scope was reportedly used on the coast, where it would have been exposed to salt air, that is not how it came to be camouflaged as a pretzel or a piece of smoked fish.

Post Extras: Print Post   Remind Me!   Notify Moderator  
actionhac
Post Laureate
*****

Reged: 08/09/08

Loc: Seattle
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5062056 - 02/08/12 11:57 AM

Great photos Joe. Good thing is where there's salt I wouldn't think you would find dreaded glass eating/etching mold.
I recently bought a C5 that the owner sprayed with Armorall. Yes it's shiny but unusable and I have a new canoe anchor. I didn't think it was that bad when I bought it but 40X is about max magnification before image goes soft and yet it looks clean after I hit it with every chemical in the house.

Robert


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5062276 - 02/08/12 01:53 PM

To understand this scope's history, study the smoking gun. It can be seen in the first images of the recent fourteen. At the upper left corners is a prominent, narrow line of caked-on sea salt inside the tube, running from the corrector back to the primary. At some point in this scope's past, it became filled with seawater. That line shows where the salt settled after the scope was laid on its side on a table to allow the seawater to drain. The line widens just slightly near the corrector, where the water pooled as it seeped out of the tube. When the condensation from all the seawater would not dry completely, the corrector and secondary were removed to open the tube to the air. These were then reassembled incorrectly, with the corrector replaced backwards. This doubled, rather than corrected, the scope's spherical aberration, resulting in its current inability to focus. The owner at the time wrongly assumed the scope was trashed from the accidental immersion, and abandoned hope of further repair.

There are many ways this sort of damage may have happened to a scope from the coast. Someone may have fallen into a tidal pool while carrying the scope back to the car in the dark... or, the incoming tide may have flooded the scope when it was left unattended for too long... or, it may have fallen into the sea while being lifted into a boat. The tripod, mount, and wedge hosed off perfectly, although the Right Ascension motors were trashed. The finder is fairly tightly sealed, so by chance no salt water entered the objective end, but its reticle was not so fortunate. Its cross-hairs were damaged in an aborted attempt at cleaning. At the time of the accident, the diagonal and oculars were in their case, not on the scope, and so remained clean.

The seller had some real knowledge of the skies, but none about telescopes. At the time, I just smiled when she told me she had never used the finder, but had only scanned the skies with this scope. One does not "scan the skies" with a C8; its field of view is too narrow to make that at all enjoyable, or even possible. She claims to have observed in the past with experienced astronomers. They would have known how to work the scope, so she had only to look through it to admire what they found. Certainly if she had found a way to use the scope herself as she claimed, she would have known it could not focus.

I suspect, but can not prove, that the seller knows the scope's history, and was glad to have found a buyer who wrongly concluded its problem focusing was due to the furthest visible object being too close due to the confines of the forest. I have since learned that Celestron's manual for the C8 of this period says its close focus is 25 feet, so that was not the problem. This is a good lesson to me: always, always test a scope over a long vista; do not buy if the seller balks at transporting it some distance to make testing possible; download and study the manual prior to meeting the seller; and, pay less if the scope is blatantly unusable in its condition at the time of sale. My mistake. Whatever she knew, the seller emailed yesterday asking how I was enjoying the scope, knowing that my friend, the buyer for her other scope, will not arrive at her door with cash for another three days.

Having deduced this history but lacking proof of the seller's exact knowledge, I'll profess to give her the benefit of the doubt. She knew nothing, including (as neither did I at the time) that her single Brandon eyepiece went a long way toward making the sale worthwhile. Nice that the tripod and wedge are good to keep or resell, even if the optics never work. In telling me the motors did not work, the seller partially met her obligation to be forthcoming about the scope's history and problems. If she knew more, partially was not enough. More importantly and within my control, as I buyer, my caution was not enough, yet I still think the story will have a happy ending.

The scope is covered with salt, not dissolved in battery acid. The salt will wash away. The corrector can be installed correctly. I will continue this thread (or start another) detailing the scope's repair and, I hope, eventual return to service.

Edited by Joe Cepleur (02/09/12 01:11 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: actionhac]
      #5062285 - 02/08/12 01:56 PM

Quote:

Good thing is where there's salt I wouldn't think you would find dreaded glass eating/etching mold.




Good thinking! A true comfort to me. Kinda like buying a Victorian home covered with ugly aluminum siding, only to find all the woodwork in perfect condition underneath.

Quote:

I recently bought a C5 that the owner sprayed with Armorall... 40X is about max magnification before image goes soft and yet it looks clean after I hit it with every chemical in the house.




Did you try denatured alcohol?


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5062288 - 02/08/12 01:58 PM

I still think you got a good deal that can be made whole again...


...but I would have gone for the Newt!

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: tim53]
      #5062379 - 02/08/12 02:44 PM

Quote:

I still think you got a good deal that can be made whole again...




So do I, thanks! Thanks for the vote of confidence... or celebration of my good luck in the end!

Quote:

...but I would have gone for the Newt!




I really like big Newts, and I want one someday, but it makes more sense now for this one to go to a friend from my astronomy club. He is going to build a new scope from its mirror to place atop his Atlas mount, which I'll be able to use. The mount from the sale may be fitted to one of the club's 16-inch Newts until the buyer is ready to house it in a second observatory he'll build for it, which will take time. When I'm ready for my big Newt, I may borrow one of the club's 16-inchers, or I may build a scope for our Thomas Cave 10" mirror, and build an observatory for the club on land I don't yet own.

So, all's well that ends well! This tale is not yet over. I'll follow through with a report of how well the C8 works after cleaning and proper assembly.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: tim53]
      #5062385 - 02/08/12 02:48 PM

Joe,
In the words of the $6,000,000.00 man -
We can rebuild him, we have the technology!

My 71/72 spent 6 months in a shallow pond (1980), not salt water, but still ruined all the electronics and something crawled over the mirrors and there is still a small water residue mark on the corrector. It then spent 22 years apart before I rebuilt it!
Is it worth rebuilding? Probably not.
(Mine was my first scope, so it has sentimental value.) Time and money spent for all of it would get you a better fork/ota. You do have a usable wedge/tripod.
(If you do ever part it out, let us know.)
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Brian Risley]
      #5062463 - 02/08/12 03:32 PM

Right now, I have three equally intelligent votes: "Be glad the salt prevented fungus from etching the glass," "It can easily be fixed," and "Cut your losses; sell it for parts and buy another."

Here's my plan:

My friend of the big Newt and I had already agreed to a four-handed optics cleaning party in honor of our new treasures. This is an excellent deal for both of us. He has an extra set of hands while working with big glass, and I get taught how to clean optics by an expert. Let's suppose I slip and destroy some of my glass (one hopes not his!). It won't be as though I trashed another friend's Astro-Physics refractor. Once the optics are removed, I'll literally hose down the metal parts. The salt should not be difficult to remove. Then I'll dry everything, clean away all old grease, and lubricate everything with the finest synthetic. After reassembling the scope, I'll truck it to the club's optician, where we'll have some fun aligning the corrector and secondary as described in an earlier post in this thread. What's wrong with any of that? Nothing!

If the finished scope works well, I'll laugh and use it. If it doesn't, I'll laugh and be surprised, but still have learned how to tear down and repair a Schmidt-Cassagrain. That, a Brandon, and a good tripod, wedge, and fork are surely worth the price paid! And, I'll be smarter next time, instead of just lucky enough.

I recall a dirty joke from my childhood: "White horse fell in the mud." There was a clean joke to go with it: "White horse fell in the sea." This scope fell in the sea, and in the ensuing efforts to dry it, the corrector got replaced backwards, or so I believe. No big deal. Maybe a blessing, since the rig did not sell for $400, $500, or more. Soon I'll know. All the worry about salt is dramatic, but it's just noise. It's salt, not sulfuric acid! I suspect not much harm was done, but will honestly report otherwise if that's what I learn.

If the optics cleaning party is fun, and in the end I have a good C8 for $250, I'll have no complaints. And, since the optics cleaning party will be fun, I'll still be chuckling even if, in the end, the C8 goes for parts to the many deserving members of this forum.

Edited by Joe Cepleur (02/08/12 03:33 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5062547 - 02/08/12 04:10 PM

I still think you got a good deal, and if you learn something about the workings of a C-8 in the process of cleaning and reassembling it, it's an even better deal.

The only thing I'd be concerned about is if the corrector had been broken and replaced with a sheet of plate glass. But it sounds as if the seller wouldn't have been knowledgeable enough to do that, so it's probably unlikely.

Even if the primary and secondary coatings are bad, OWL still has a 50% off deal going that you might want to consider. Then, you could wind up with an essentially "new" orange tube C-8 for about $350. Still a good deal.

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5062654 - 02/08/12 05:26 PM

Joe,
Don't give up on the motors either. You can take the gear boxes apart either by unsoldering the case or just bending the taps back. A good cleaning and some fresh grease my be all they need.
I fixed a couple of motors this way. I even fixed a gear inside the gear box missing a couple of teeth by pressing it into modeling clay to make a mold, turning the gear in the mold so the missing teeth were positioned were the impression had some good teeth and using a couple of drops of epoxy to form new ones. That motor is a very rare one with a built in clutch on the output shaft and used on my Jaegers mount. It has been working without problems for a couple of years now.
My C-14 spent a good part of it's life outside and the corrector had green slim growing half way up it and it cleaned up perfectly. Here is a link to the old C-8 I'm restoring now and it was also in pretty bad shape when I first got it and cleaned up very well. old C-8

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: tim53]
      #5062752 - 02/08/12 06:37 PM

This morning under bright sun, I saw on the corrector some of the greenish/purplish reflections that one expects of the C8's "Special Coatings," which are antireflectives. Furthermore, if anyone had replaced the original corrector with plate glass, would they, or how would they, have so perfectly matched the salty coating of the new glass to the rest of the scope? I have the original corrector.

After I get the scope working, as I assume I shall, I'll evaluate it, and possibly have OWL recoat the mirrors. I do not expect they will be especially damaged, but how much reflectivity would they have lost just due to time? These mirrors are thirty-five years old. To pull a number out of thin air, if they were now only 67% reflective, then my C8 would perform more like a C6. That would be a good reason to recoat the mirrors.

What about the RA axis? For $30 at Astro Parts Outlet, I could buy the parts to fix the manual slow motion control, and live without motors in my current mount, which is okay with me. I could also spend $150 to replace the entire housing with gears and motors, or $225 for a housing complete with Byers worm gear drive. Anyone know a less costly source? Or, reading a post that arrived while I was writing this, I may be able to fix the motors I already have!

How much is that Brandon worth? Total potential investment in C8 could then be said to be:

$250 - (value of Brandon and other accessories) + ($50 in various bolts and parts) + (cost to recoat mirrors) + (cost of new motors)

Those last two expenses would be nil if I chose not to incur them. Then again, if the optics were excellent, a fully restored C8 would be cool, and a far better teacher than the new ones with computerized mounts!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5065065 - 02/10/12 08:33 AM

With special thanks to Lady Cepleur, the obvious next step is to reverse the corrector, even prior to cleaning, to test whether that allowed the telescope to be brought into focus. Trouble is, the corrector can not currently be removed, because the Allen bolts attaching it to the scope are frozen. Might anyone know any tricks for loosening them?

There may be a special problem due to the salt water damage. I've been reading about cleaning salt water deposits from glass and metal. (Lots of information is available in the context of cleaning salt water aquariums.) Sea salt is not as innocent as table salt. It contains minerals that harden remarkably solid. Fortunately, they are soluble in white vinegar, so one solution would be to soak the corrector end of the tube in a tub of vinegar overnight. I'm thinking this would do no further harm than the salt water already has, and that, eventually, the entire scope may need a long soak in vinegar. Can anyone think of a better idea, or a good reason not to do this?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: tim53]
      #5070213 - 02/13/12 10:32 AM

Quote:

I still think you got a good deal, and if you learn something about the workings of a C-8 in the process of cleaning and reassembling it, it's an even better deal.




Thanks, Tim. I found another thread of yours showing your beautiful reconditioning of a scope with worse beginnings, and was truly inspired. I'm thinking now, "Yeah; if Tim can fix that, a little penetrating oil, some time, and elbow grease should restore mine." May required a little more cash, but it will be worthwhile in the end.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5070221 - 02/13/12 10:38 AM

This thread segued to the Cats & Casses Forum. A specific question there about loosening frozen bolts near the corrector generated a great deal of input. I will continue here in Classics as the restoration proceeds.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5072205 - 02/14/12 02:16 PM

Progress! The question at Cats & Casses about removing the frozen bolts without breaking the corrector morphed into ideas on how, finally, to get the scope to focus. The corrector was not reversed, but the secondary housing had been floppy, distorting the light path. The scope now yields impressive close-up views of objects over a mile-and-a-half away across the lake.

I had also asked a question on the Eyepieces Forum that lead to a discussion about dating not just the Brandon that came with the C8, but those of other members as well. Mine appears to be among the original Vernonscopes from the early to mid 1960s, the third model produced. I do not believe it sold with the scope from the factory, but am glad it somehow found its way into my kit.

Looking around old Classics posts, I've seen far worse C8s successfully restored. With mine now focusing, I am confident mine can be restored, too, and will post its progress here.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5076727 - 02/17/12 10:15 AM

A daring friend and I are preparing to disassemble the C8 for cleaning. I know the importance of marking the corrector, to assure that it is reassembled in its exact, original orientation. What about the primary mirror? Will it attach in only one orientation, or can it rotate if we are not careful?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5077145 - 02/17/12 02:05 PM

It should be secured to its mounting plate. The focus shaft allows it to only go in one way. The mirror should have RTV around the central hole, so even removing the lock ring should not allow it to move.
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Brian Risley]
      #5077170 - 02/17/12 02:23 PM

"RTV" -- What's that? On Google, I found a silicone adhesive used for gaskets. Do you mean that, in addition to the locking ring, the mirror is secured with some kind of silicone adhesive? How would I unstick that?!

And, would it mean that, upon reinserting the mirror, I should put a dab of fresh RTV?

I imagine this goo is used to prevent the mirror from shaking around and getting damaged, despite the close tolerances.


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5077181 - 02/17/12 02:28 PM

The RTV was put in to keep the mirror centered. I wouldn't remove it, but see if you can clean the assembly assembled.

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: tim53]
      #5077483 - 02/17/12 06:13 PM

Okay, thanks. So, the RTV is the glue holding the mirror to its carrier in the assembly, as seen at the bottom of the page in a five-year-old article on Astromart by Greg Nowell showing how to disassemble a Schmidt-Cassegrain:

C-8 Mirror Assembly

Getting ahead of myself, if the mirror must be carefully centered on that assembly, what happens if it needs to be recoated? Can an upstart wannabe telescope restorer successfully center a mirror at home?

Edited by Joe Cepleur (02/18/12 05:16 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5078371 - 02/18/12 11:22 AM

Joe,
The RTV is in addition to the metal retaining ring/cork shim that you see. It is between the glass and the shaft and often some leaks around the back and is often visible.
Centering and making sure it is square is a bit of a trick, square can be done if you have a turntable or lathe (That is level) and can spin the mirror assembly. If you point a laser at it, the reflection should not move when you rotate it. There may be a large rubber O-ring underneath that helps keep it centered, but one can also measure from the inside edge of the tube to the mirror edge all the way around. One must also be sure the RTV replacement does not outgas much.

Unless you remove the mirror from the cell assembly, you should not need to worry about the RTV.

You will want to lube the shaft/inside of the mirror focus tube assembly. This makes the focus smooth and helps with mirror flop. Again, use a lube that will not outgas much. Some recommend the Corning High Vacuum stuff, others say the SuperLube grease (not the spray) and other say a Mobil1 grease. You want something that won't run at higher temps or solidify at lower temps.

Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Brian Risley]
      #5078471 - 02/18/12 12:36 PM

Centering the mirror sounds tricky. I've written to Optic Wave Labs asking whether I could ship the mirror on its base, and have them reattach and center it after coating.

Looking at the mirror while its still in the tube, I'm seeing many tiny areas that look scratched. Perhaps the salt did that, or a crude prior cleaning. I'm sure the scope could work as is with the mirrors only cleaned, but looking at the partially peeled coating of the secondary, it couldn't hurt to get them restored to better than new condition -- especially at half price.

The DOW reached 13,000. Gotta hurry, we'll all hope, before it reaches 14,000, and OWL's price for recoating doubles back to normal!

Next vexing bit o'foresight: I understand about marking the corrector and tube with tape, to assure proper alignment upon reassembly. Trouble is, cleaning the mirror is likely to remove the tape. Any solution? I had thought of using duct tape or some other waterproof tape, but only at the very edge, the part covered by the corrector's retaining ring, so any residue would not show cosmetically or alter the image.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5078777 - 02/18/12 03:56 PM

There should be alignment lines (usually blue) on the back of the secondary and the primary that will allow you to get them back into orientation with the corrector serial #. The primary mark should be located opposite the focus shaft. This ties the optics to the back cell.
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Brian Risley]
      #5079655 - 02/19/12 07:06 AM

Quote:

alignment lines (usually blue) on the back of the secondary and the primary that will allow you to get them back into orientation with the corrector serial #




I can picture that, thanks. How precisely must they be aligned? It should be fairly easy to get the secondary pretty close to perfect with the corrector, because they bolt together. What about aligning that assembly with the primary? Obviously, a careless 50° out alignment would hurt, yet eyeballing components that are stuffed into a tube over a foot apart may be difficult to get perfect. I've read that, in collimating this scope, a fraction of a turn of a collimating screw could make a big difference. Is the alignment of these components as touchy? Does it need to be perfect, or just close enough?

Hard to believe that, yes, somehow I'll fix this scope, and then I'll be the one answering these questions for others in the future!


Post Extras: Print Post   Remind Me!   Notify Moderator  
cheepnis
super member
*****

Reged: 02/16/08

Loc: Columbus, OH
Re: The Plot Thickens: Fixing a Salt-Encrusted C8 new [Re: Joe Cepleur]
      #5080800 - 02/19/12 06:25 PM

Great links in this thread, I'm making a bookmarks folder for all this good info.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Inspecting a C8 Prior to Purchase new [Re: Geo.]
      #5081586 - 02/20/12 08:42 AM

Rereading this thread to consolidate all I have learned, I am struck by George's comment from the first page:

Quote:

Only a few orange Super C8s were StarBright, so the coatings of this C8 will be either standard Al SiO2 on the mirrors and perhaps antirefective on the corrector ("Special Coatings"). Starbright is noticably brighter than the standard coatings. So the light thruput of an orange C8 is about the same as a C6 XLT.




Margarita has special coatings... Sorry; better explain that. Amicus Sidera asked:

Quote:

...have you considered christening that salt-encrusted C8 as "The margarita Scope"?




I like that. I don't usually name objects other than boats, but in this case, we'll call her "Margarita!"

Margarita has special coatings, but it sounds as though to get not only the resolution, but also the full brightness and reach of the 8" mirror, I should ship the mirrors off to OWL before the DOW hits 14,000 again, regardless of the condition they appear to be in after cleaning. I mean, it would be awful if the DOW rose so high, but I were behind the times, wouldn't it? Imagine the horror if, after all the work to fix this thing, I could afford to buy a new one, or a fully restored classic, instead! Horrors! Whatever the economy, it makes sense to spend a hundred bucks to effectively gain two inches of aperture.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5133621 - 03/21/12 12:57 PM

Hard to believe a month has passed since I last posted about Margarita. Four stars had to align before I was able to proceed.

First, in a bout of buyer's remorse, I began to wonder whether she were a financial boondoggle after all. Looking ahead to the cost of recoating the mirrors and possibly buying a Byers worm drive, might it have been fiscally sounder to simply rejoice in the Brandon, ortho, and even the Kelners that came with the scope, sell the rest for parts (the tripod and wedge would each eBay for about $100), and then buy another old orange tube that was ready for use? I watched prices on eBay for a while, and decided, "maybe, maybe not." Then there was the trouble beyond cost. If I sold what I had, I'd also lose the experience of restoring a classic, which, while a fun pain, was priceless.

Then, after I found a way to brace the secondary prior to disassembling the scope, my club's optician collimated the optics. They won't hold until the secondary support is properly fixed, but it became evident that, yes, under the salt, Margarita is a perfectly fine C8! No such guarantees if I sell her for another. He is also a wizard of mechanics. We're going to add a manual slo-mo worm gear to the polar axis. This slo-mo will be better than the stock spur gear version anyway.

Finally, winter has come to an early end, so I have been able to turn the running water back on in the house. Been lugging washing, flushing, and drinking water all winter, and heck if I were going to drag enough extra to clean a telescope! Remember, it's not just the mirrors that need a rinse, but the whole salty mess. Now when I get her apart, into a padded sink she'll go, for a bath of the finest running well water, followed by a carry-in rinse of distilled.

The end of winter also means I can work on her outside, which is important with chemical sensitivities in the household. Figuring I could always return to PB Blaster, I bought a DuPont Teflon Penetrant instead. It's low odor, and it is sold with its own eyedropperish bottle. No need to transfer a spray can of PB Blaster into an eyedropper before I began. The penetrant has already opened all of the bolts except those on the corrector, but those have been soaking for a few days, so I'll try again soon.

Never would have anticipated that I would have become a convert to Cassagrains, but I'm pretty excited. It won't be as fine optically as Caveman's 9-inch, unobstructed refractor, but in exchange for acceptable optical trade-offs, I'll get a seven-and-a-half foot long telescope that magically fits in my car and carries outside easily, and a matching seven-foot tall, two-hundred pound pier that weighs nothing and nestles into the trunk. How cool is that? And, it'll have classic cache to match its optical prowess, making it in that regard better than new!

I'm amazed the more I study the C8. It's really a pretty simple device, if one made to exacting standards through a complex manufacturing process.

I'm sure you've all heard about the loss of Tom Johnson, founder of Celestron, whose solution to the problem of making corrector plates inexpensively caused the Cassagrain revolution. This one's for him!


Post Extras: Print Post   Remind Me!   Notify Moderator  
PhilCo126
Post Laureate


Reged: 01/14/05

Loc: coastline of Belgium
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5137006 - 03/23/12 11:46 AM

Looks like a " restoration project " scope

Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: PhilCo126]
      #5157395 - 04/05/12 10:33 AM

any updates? pix?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5158004 - 04/05/12 05:27 PM

Quote:

any updates? pix?




Thanks for asking. I had to leave the scope 200 miles behind to help my mother through a bout in the hospital and the rehabilitation afterwards. She'll be fine, but this is about the only thing that could attain a higher priority in my life! Good news is, all those screws are getting a good, long soak in the penetrating oil. Upon my return, I'll post a picture that I've already taken, showing the crazy workaround steadying the otherwise floppy secondary while its screws are frozen too loosely.

Any votes for the best finder for a C8 for purely visual work? Reflex sight? 9x50 right angle, correct image?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531807 - 11/21/12 09:43 AM

Time to send Margarita for repair, but it's taken a while to find a crate that would guarantee safe shipping.

At some point in his life, the wanna-be restorer of telescopes must either become a proper machinist, or accept the fact that he is in over his head. It's one thing to see Tinky resurrected or to witness the rebirth of a Cave found in a field while horseback riding, but entirely another thing to make similar events happen. This scope's problems are nothing someone with the right skills and tools could not fix easily enough, but I an not destined to become that person any time soon.

I have been concerned about shipping my C8 ever since reading, in the instruction manual for a similar Meade 2080, that a Schmidt-Cassegrain should never be shipped solely in its foam-lined storage trunk. Always, Meade insisted, pack the trunk inside the original Styrofoam-lined, corrugated cardboard shipping crate. I have read elsewhere that there is a risk of breaking the corrector plate when jostling the scope in shipping. This is solely a problem of inertia. Drop that crate, and the sudden stop when scope hits concrete depends upon the strength of the corrector to hold both its own momentum and the secondary's. Bounce it too hard, and the corrector could break, even if the outer box and inner trunk were unscathed.

Having found the perfect crate readily available at appliance stores everywhere, I thought I'd show how I packed the scope for confident shipping. It may be overkill, but it was easy once I knew how, and try replacing a forty-year-old corrector if you lose one! Margarita's progress will continue to be posted to this thread. Check back often, same Bat-time, same Bat-channel!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531809 - 11/21/12 09:45 AM Attachment (36 downloads)

Margarita in her trunk, in need of a proper outer protective crate.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531837 - 11/21/12 10:02 AM Attachment (21 downloads)

All the materials needed to encase Margarita in a proper ark for shipping.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531847 - 11/21/12 10:09 AM Attachment (22 downloads)

A hunk of Styrofoam wedged below the mount snugs Margarita in to her trunk, so she won't shift in transit.

After much searching, I found an ark with Styrofoam cradles that perfectly fit a C8's trunk. Ask your local appliance store for the box from an undercounter microwave oven.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531850 - 11/21/12 10:10 AM Attachment (21 downloads)

Popped her back out of bed for a moment, to affix her lens cap more securely. (Note the clear packing tape now fastening her lens cap to her tube.)

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531862 - 11/21/12 10:15 AM Attachment (18 downloads)

A rolled up newspaper doubly secure the lens cap, by wedging it against the mount.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531868 - 11/21/12 10:19 AM Attachment (15 downloads)

The trunk is now set it into the shipping crate, sandwiched between the Styrofoam cradles. The fit is not quite perfect. Note the several inches of cardboard wall extending above the top of the Styrofoam.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531896 - 11/21/12 10:33 AM Attachment (16 downloads)

Peanuts would fill the space perfectly, but make a mess upon opening the crate. What to do?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531906 - 11/21/12 10:38 AM Attachment (16 downloads)

Rather than pour the peanuts loosely, they were sealed in a plastic bag, so they may be removed and repacked in one piece. (The picture shows the peanuts before the plastic bag was taped closed.)

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531908 - 11/21/12 10:39 AM Attachment (16 downloads)

Details count! No sacrilege may be inscribed onto the ark!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531922 - 11/21/12 10:45 AM Attachment (15 downloads)

The magic words must be inscribed onto the ark prior to its being presented to The High Priest of Repair. Can you say, "Primghar?"

"Primghar, Primghar, Primghar..."

The complete spell (for Google; you humans can read it below) is:

Larry Beach
Clear Edge Optical
215 Third Street Southeast
Primghar, Iowa 51245


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531934 - 11/21/12 10:48 AM Attachment (18 downloads)

The ark was then ready to be presented to the high priest.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531938 - 11/21/12 10:50 AM Attachment (17 downloads)

A second ark was soon readied, to preserve for Margarita all the possessions necessary in the afterlife. The 10x50 finder from a C11 hopes to be fitted to Margarita in addition to the traditional 6x30, to grant her powers of discovery beyond those of ordinary mortal scopes.

Edited by Joe Cepleur (11/21/12 02:34 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531948 - 11/21/12 10:52 AM Attachment (21 downloads)

Some of Margarita's possessions are inscribed with magical words of their own. The high priest has been begged to restore to health whatever he can. (The corrosion ate away some of the castings and coatings.)

Edited by Joe Cepleur (11/21/12 02:28 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531952 - 11/21/12 10:54 AM Attachment (16 downloads)

The ark and arkette were then ready for passage into the netherworld. (The items in the arkette were packed in lots of crumpled newspaper. The objective was removed from the 10x50 finder and wrapped separately, for extra safety.)

Edited by Joe Cepleur (11/21/12 02:21 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531956 - 11/21/12 10:55 AM Attachment (19 downloads)

Dang! A few screws accidentally not packed into the arkette were sent to the high priest in an epistle.

Edited by Joe Cepleur (11/21/12 02:37 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531965 - 11/21/12 10:57 AM Attachment (16 downloads)

Classic scopes artfully encased in arks *must* travel solely in cars appropriate to their era, lest the magical spell ensuring their safe return be broken.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531971 - 11/21/12 10:59 AM Attachment (19 downloads)

The high priest was correct in his suggestion that I'd save a fortune shipping via insured Parcel Post, not UPS or FedEx. $56.41 shipped the lot, which is dirt cheap compared with other services. Should travel the light years to the high priest in about a week.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5531974 - 11/21/12 11:00 AM

At this stage, after long and nervous delay, I am finally confident of the safety of Margarita's corrector plate as she voyages to the high priest. If I could travel back in time, I would have no trouble handing either ark or arkette to Joe Namath to use as the football in the closing minutes of The Heidi Game.

The high priest may post images of his own to this thread. If not, I hope to report back in about a month. Same Bat-time, same Bat-channel!

Edited by Joe Cepleur (11/21/12 11:09 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Holland
Carpal Tunnel


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5532008 - 11/21/12 11:18 AM

I wish Margaritta well on her magical voyage, and trust that she will return to you with powers anew to gaze into the past.

Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: Ed Holland]
      #5537195 - 11/24/12 12:49 PM

I got the screws in but not the scope yet, I will be posting pix as I remove the components. This is going to be my biggest challenge to date, The frozen motors a particular challenge but I will try to keep her as origonal as possible.
She will be getting a new set of optics, at least for now!
the origonals will be getting recoated,(I Believe)..
.....More to come....


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5537218 - 11/24/12 01:07 PM

Looking forward to following the restoration, hope all goes well.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5546332 - 11/29/12 09:55 PM

Larry received the envelope nearly a week ago, a few days after I mailed it, and the box with eyepieces yesterday. No sign yet of the scope itself, nor can I track it. So much for paying for a tracking number. The post office says I'll only be sent a receipt via SnailMail after Larry receives it.

The eyepieces that look like junk likely are, but we may save one or two. The steel barrels are corroded onto the white metal castings, and many of the coatings are shot. This was as I suspected, but, hey -- send 'em to the master for an appraisal!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5553048 - 12/03/12 10:55 PM

Larry received the scope today. The outer box was trashed and the inner trunk had a new, nasty gouge, but the scope inside was unharmed! His partner in crime had taken his drill to work --can you imagine the nerve!-- so he was unable to start dissecting the frozen corrector.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5553245 - 12/04/12 02:00 AM

Thanks for the update, Joe. Glad to hear Margarita arrived safely, even if her carriage was a bit roughed up! Looking forward to seeing lots of pics of her rebirth.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Holland
Carpal Tunnel


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5554025 - 12/04/12 01:44 PM

Wow. The first leg of an epic journey. I await further installments of this tale of adventure

Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: Ed Holland]
      #5554047 - 12/04/12 01:53 PM

Got the scope in yesterday, there was a chunk out of the box about the size of a brick! Thankfully it was packed well,
First thing is to drill out the corrector retaining screws, 2 months of soaking in PB Blaster didn't help any.
more to come....


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5564142 - 12/10/12 01:04 PM Attachment (32 downloads)

I got the corrector off and it wasn't as bad as I thought there was some Oxidation on it, I used some very fine polish and it took most of everything Windex wouldn't. I have 1 Corrector ring screw thet I need to get out but I had to order a new Tap..

Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5564147 - 12/10/12 01:05 PM Attachment (35 downloads)

All windex would take off

Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5564156 - 12/10/12 01:09 PM Attachment (30 downloads)

corrector off

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5567254 - 12/12/12 10:02 AM Attachment (27 downloads)

Larry will post occasionally himself, but he wants to focus on repairing, so I'll be the Webmaster. He'll email me progress reports, and I'll edit and post 'em. Sorry for the delay in Webmastering -- my eMail took a vacation over the weekend, with some of the messages just now reappearing. So, that puts this update out of order with Larry's prior post, but interesting, I hope, nevertheless.

Here's Larry's report on his epic battle with the screws holding the retaining ring. Because this was a salt-encrusted C8, corrosion between the steel screws and aluminum ring had frozen the threads hard:

"I got the retaining ring screws drilled out today, it was a tough slow process, the bit size I had to use are easy to break. The Celestron screws are surprisingly hard. On the other hand, the ring is soft. I dinged the holes in the ring a bit, no way around it. The 2 spots should mostly cover up, but if you want it to look perfect I can try to find another ring. Up to you. The other ring I have is plastic. I am going to try and soak them a bit more then try to use a small pair of vise grips I have."

We'll be keeping the scarred metal ring as a badge of honor, as well as a better alternative to some plastic replacement. Amazing those screws are so hard. Must be a way to keep such tiny shafts from snapping. Here's a photograph of the ring, showing the scars. Personally, I'm impressed, given my first-hand knowledge of how tightly they were corroded in place. Remember, it was my inability even to remove the retaining ring that made me seek professional help in the first place. No way did I want my first attempt at drilling out screws to be so near to thin glass!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5567273 - 12/12/12 10:20 AM Attachment (26 downloads)

Everyone loves action photos, so here's one of the retaining ring caught in the act of being pulled. Dig that salt under the retaining ring! Must have been hard as epoxy:

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5567700 - 12/12/12 02:21 PM

Quote:

No way did I want my first attempt at drilling out screws to be so near to thin glass!




Yes, not something I would fancy doing. Well done Larry

Glad to hear you're keeping the metal ring and not going for plastic. The battle scars give personality.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Holland
Carpal Tunnel


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5568211 - 12/12/12 08:10 PM

Great pictures. The "salt" you see may also be aluminium oxide corrosion. I've seen similar encrustation on alloy bicycle frames, after riding on salt treated roads in the UK. The good news is that in this situation, it will be removed quite easily and shouldn't upset anything anyway.

As for the retaining ring, some suitably sized washers, in black oxide finish, might be a good choice if you wish to hide the marks.

And lastly, well done to Larry for his skill and perseverence in removing the screws - a ticklish job indeed

Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: Ed Holland]
      #5568287 - 12/12/12 09:10 PM

Thanks Ed there should be more pix tomorrow, one of the motors were totally packed with rust, Unbelievable after 2 hrs work it runs better than the clean one??!!?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Ed Holland]
      #5568331 - 12/12/12 09:38 PM

Quote:

The "salt" you see may also be aluminium oxide corrosion. I've seen similar encrustation on alloy bicycle frames, after riding on salt treated roads in the UK. The good news is that in this situation, it will be removed quite easily and shouldn't upset anything anyway.




Sodium Chloride begets Aluminum Oxide via a bimetallic chemical reaction? That would explain the mess of frozen threads! Interesting to hear it's a known reaction. Glad to hear it will prove ultimately harmless.

Quote:

As for the retaining ring, some suitably sized washers, in black oxide finish, might be a good choice if you wish to hide the marks.




Excellent idea, thanks! Let's do it, Larry. I'm all for battle scars, but never against making things look neat.

Philips heads to secure the corrector... Hhmmm. Might it be better to buy Allen heads? With Phillips, the screwdriver can slip easily, possibly damaging the corrector. I'm not worried about your assembly, Larry, but my own work someday, when I remove the corrector to remove whatever might have fallen inside the tube.

Quote:

And lastly, well done to Larry for his skill and perseverance in removing the screws - a ticklish job indeed




I sent the scope to Larry after a few fellow members suggested he might fix it. It was not a terribly studied decision, but more the feeling that if some others had been happy with his work and I was never going to fix the scope myself, no harm done. Having seen the pictures and read the stories that he sent me today, I have the feeling I've stumbled across a real master. This pleases me to no end, since I really do care about the scope, and want to see it restored beautifully.

Sorry to be too tired to post more now. Bedtime for Bonzo, but I promise this thread will be well worth following. You'll be as amazed at Larry's pictures and stories as I am.


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5569085 - 12/13/12 11:37 AM

Larry's a good guy, and very knowledgeable about these puppies. I think you made a good decision, and it's always heart-warming to see one of these saved. I know they're plentiful, but every year they're getting less so!

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Restoring a C8 After Purchase -- Update new [Re: tim53]
      #5569276 - 12/13/12 01:23 PM

With the corrector off, this is good time to Foucualt test the primary. It should be spherical or close to it. What is critical is that the figure is smooth. If not your wasting your money getting it recoated without refiguring it.

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: DAVIDG]
      #5570873 - 12/14/12 01:36 PM

Upon removing and studying the mirrors, Larry finds that they are pitted. There must have been some weird, corrosive reaction between the aluminum and the salt. One would think the Pyrex substrate would be unaffected, but apparently that's not the case. The scope will be receiving new StarBright mirrors from... my history here is slipping... an era that Larry says should have good optics. An earlier black tube, with an orange cosmetic cover over the secondary. The original mirrors may be okay for a determined home-builder to polish and use again.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5570876 - 12/14/12 01:39 PM

Hi Joe, that's a shame about the mirrors - good that you have a replacement source though. Will you be swopping the corrector as well?

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5570946 - 12/14/12 02:34 PM

This will be a Frankenscope. The StarBright mirrors are available because their corrector was shot. We'll be using the original orange C8's corrector with the StarBright mirrors. Tests will show how well they match. It will likely be just fine, at least good enough -- maybe great!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5570973 - 12/14/12 02:53 PM

Fingers crossed! It's good to hear that Margarita will carry on!

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5571284 - 12/14/12 06:23 PM

On these old Celestron scopes, the primary and secondary are matched, because errors in the primary were corrected by tweaking the secondary. This was a convenience of manufacturing. The 5x convex mirror could be slightly flattened here and there, so that 1/5 the grinding would induce the necessary corrections. This was much easier than reshaping the entire bowl of the concave primary, or than trying to tweak just a concave section.

The correctors were mass produced, and could vary slightly. If one did not test well, it was rotated; if that did not fix the problem, a different corrector was substituted. By far, most of the fuss was in matching the mirrors. It's not that the corrector was unimportant, but that they were remarkably consistent. Margarita will likely be just fine.

If you look back at the pictures and read his description, Larry did a remarkable job in refurbishing Margarita's original corrector. After about two hours with Novus Three Step Polish and a few special additives of his own, it cleaned up beautifully.


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5571469 - 12/14/12 08:12 PM Attachment (43 downloads)

Actually Jon hasn't seen a pic of the corrector after I hand rubbed the oxidation from the multicoatings, I was surprised that they cleaned up as much as they did,
I use the Novus system and I add different percentages of Cerium Oxides, Cerium NANO Oxide, and fine powdered Aluminum Oxide. mixed in as my own "slurry recipe" tried and perfected through the years from my first days working in an Optical lab, grinding and polishing lenses.
here is the "after" result of the the carefull hand polishing, I actually use a converted lensometer to measure the aspheric gradient power so not to change it. I marked the "Plano" side in different colored dry erase marker showing the gradient steps of power
There is some dust as I sat it onto the empty OTA.
The lighter and darker uneven area isn't the coarings but the Ultra Black paint drying in thicker areas.. You can see the difference from the pictures on the top of the page showing it as a nearly Charcoal powder look.
I'm very happy with it.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5571947 - 12/15/12 02:30 AM

Gosh, that has cleaned up amazingly well, a big change from the salt encrusted shots a couple of days ago.

Looking forward to seeing the rest of your work over the coming days.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5571961 - 12/15/12 03:01 AM

That's interesting, I hadn't realised that Celestron had managed to get that level of consistency in making the correctors. Tom Johnson's master block process really opened up SCT mass production.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5572294 - 12/15/12 10:20 AM

It wasn't that difficult once he got the basic shape of the mould down,
They put a flat blank on a mould of the aspheric corrector shape, then they placed a very thin cloth over the bottom of the mold and set a very high vacuum. (*This simple step is the basis of the Lawsuit between Celestron and Criterion which due to the overwhelming legal costs helped Criterion to its demise).They then polished the top of the blank which had formed to the mould flat.
when the vacuum was removed the glass had the aspheric curve.
an amazingly simple but brilliant process.
*I suggest reading the minutes from the Lawsuit on Google, it is very interesting reading, But basically ended pretty much in a tie but Criterion made some consessions to end the litigation.

http://www.leagle.com/xmlResult.aspx?xmldoc=19781064461FSupp603_1970.xml&...


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5572666 - 12/15/12 02:10 PM

Hi Larry,

Thanks for the link to the Celestron - Criterion court case, made for some very interesting reading and it has filled in quite a few gaps in my understanding of what happened. I see there was a further report a few years later in 1982

http://www.leagle.com/xmlResult.aspx?xmldoc=19821164552FSupp612_11075.xml&....

I've also found the patents issued to Johnson and O'Rourke of Celestron and John Krewalk Sr of Criterion to be interesting reading.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5573099 - 12/15/12 08:02 PM

Quote:

The correctors were mass produced, and could vary slightly. If one did not test well, it was rotated; if that did not fix the problem, a different corrector was substituted. By far, most of the fuss was in matching the mirrors. It's not that the corrector was unimportant, but that they were remarkably consistent. Margarita will likely be just fine.






Joe,
I've refigured a number of SCT optics and designed and fabricated optics for over 30 years now. Both the primary and corrector have residue errors. They were placed in a test fixture and the secondary aspherized. The exact amount of aspherizing needed was variable since it has two functions. One was to remove the errors of all the elements and the second function was to fully correct the system to remove the spherical aberration. So replacing one corrector with another requires that the secondary again be refigured to remove the errors in the system. The correctors had the same amount of variablity as the primaries. The reason was that each master block that was used to make the correctors had some variablity in it's exact surface and they would also wear from use. The other source of variablity was the "flat" surface of the corrector. In theory these should be optically flat but in reality they almost always never are and can vary by a number of wave concave or convex. This results in the corrector either under or over correcting the wavefront from the primary. The reason why it is not a problem is, because all three elements are corrected together by figuring the secondary. The image in your scope won't be a fuzzy mess but the odds are low that it will be anything more then around 1/2 wave at best. If you want better your going to have to refiguring the secondary to correct the complete system.

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: DAVIDG]
      #5573176 - 12/15/12 08:40 PM

From what I havve seen Celestrons Correctors were more consistant than the other commercial offerings in that era.
Meades and Criterions were all over the place.
I got the system together and have first light through it,
It will be at least defraction limited..
This is a very fun project, I feel honored Joe trusted me to do the work for him.
Larry


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5573224 - 12/15/12 09:06 PM Attachment (26 downloads)

What method did you use the test the variablity of the correctors that you worked on ? What method are you going to use to test the overall optical correction when the scope it is assembled to varify the results ?
Here is a picture of vintage C-10 corrector plate that I'm testing against a Master 12" optical flat by interference. This test showed the corrector was astigmatic. Like I said I have actually tested and refigured these type of optics, using the correct optical tests to determine the optical correction. The odds will be low that any mix and matched SCT optical set will be diffraction limited without refiguring at least the secondary.
Celestron understands that their optics have variablity and need to be figured as a system. This is why they won't sell individual elements.

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update *DELETED* new [Re: DAVIDG]
      #5573282 - 12/15/12 09:42 PM

Post deleted by orion61

Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5573386 - 12/15/12 11:02 PM

A Foucault tester can only be used to test the primary not the complete system of a Schmidt cassegrain. To test the overall correction one needs to do a test like double pass autocollimation.
I'm just trying to make sure that false information about these system doesn't keep getting spread that one can just swap a corrector in and the optics will be automatically diffraction limited. That simply is not the case. You can rotate the elements all you want and that doesn't do anything to the spherical correction. So if the corrector doesn't match with the primary and secondary that isn't going to fix the problem.
You made the statements that the Celestron correctors you have seen have less variablity then others and the system will be at least diffraction limited after you installed the optics. I just asked how you determined this. If your statement has any validity, then you should have no problem providing the methods you used to collect this data so everyone can understand the strength or weakness of your claims.
Narcissism, no just someone who has actually worked on Schmidt cassegrain systems, designed and fabricated precision optics for many years, won a number awards as proof of my expertise in the subject, as been teaching mirror making for about 20 years now, being a consultant on optics like my most recent input on "Telescope , Eyepieces and Astrographs" for the authors and Willmann Bell Publishing, another first place in the optical judging at Stellafane this past year and just had an article in Nov issue of Sky and Telescope about telescope making.

Happy Holidays,

- David Groski


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: DAVIDG]
      #5573504 - 12/16/12 01:12 AM

DavidG, thank you for your input. I think you're saying that the scope will work with the mix n' match parts, it will show an image at the eyepiece, but it's not guaranteed to be as good as a C8 should be.

Larry, I don't believe DavidG was insulting your eyes. He was only warning that, in mixing and matching parts, we may be less lucky than we had hoped. Why don't we skip to Plan B, and ship the original mirrors for evaluation for a cleaning and recoating? You said earlier today that the mirrors were not pitted as badly as you had thought at first. Perhaps they could be used, keeping everything original. If not, we continue with the mix n' match parts.

Let me guess: Polishing the mirrors would alter their surfaces, requiring refiguring of the secondary to match the system's new abberations?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5573751 - 12/16/12 08:57 AM

DavidG, looking at the picture of your 10" corrector, an arc of stacked, squiggly lines runs through it, and there is a puddle of splotchy light off to the right. (Highly technical description!) Are those the aberrations that, for this particular corrector, would be countered by specially aspherizing the scope's secondary? I understand that, actually, the fix only works when the primary is also in the optical train.

Suppose my scope, if assembled to current plan with mix n' match optics, were only 1/2 wave (which, itself, may not be guaranteed). What would be the significance? Is, for example, the difference between 1/2 wave and 1/8 wave the difference between recognizing Jupiter in the eyepiece, and being wowwed at the detail in its cloud bands?

I'm interested in everyone's thoughts, and do not presume opposing views as being attacks on each others competence. I see this as a practical exercise. It's not surprising that a perfectly matched set of optics would be ideal, so the question becomes picking the best solution among five:

(1) All new optics (expensive -- beyond budget for now!)

(2) Mix n' match

(3) Refurbish original optics (if possible; maybe also expensive?)

(4) Anyone know how to refigure the secondary?!

(5) Quit (why? we've come this far, and at least will have working mechanicals with the potential for improved optics later)


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Update new [Re: DAVIDG]
      #5573791 - 12/16/12 09:29 AM

I have deleted the above reply to get back to the Nature this Post was intended which is to get a frozen up unuseable scope back under the stars with as little expence as possible as a pet project.
All I can say is that I am very encouraged with the results so far by viewing the in focus airy disc and intra and extra defraction patterns. The final product will speak for itself.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5573865 - 12/16/12 10:12 AM

Years ago, when I was a student in London, I was advised to visit the viewing galleries at the law courts. It's a fascinating spectacle. The barristers are required, by law and custom, always to address each other's comments as plausible; and, upon disagreeing, to refer to each other as "our learned friend." Let's keep our discussion at that level.

Given how close my scope is to assembly with the original corrector and StarBright mirrors, would there be a way to post pictures of its star tests? Larry, could you replace the eyepiece with a camera, or digiscope a decent image?

I'm grateful to both of you, to Larry for his passionate commitment to a workable, practical, affordable rehab for this grand old scope, and to Dave, for the considerable time invested in offering his technical input to our endeavors.

Thank you,

Joe


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5575516 - 12/17/12 10:52 AM Attachment (16 downloads)

Quote:

DavidG, looking at the picture of your 10" corrector, an arc of stacked, squiggly lines runs through it, and there is a puddle of splotchy light off to the right. (Highly technical description!) Are those the aberrations that, for this particular corrector, would be countered by specially aspherizing the scope's secondary? I understand that, actually, the fix only works when the primary is also in the optical train.

Suppose my scope, if assembled to current plan with mix n' match optics, were only 1/2 wave (which, itself, may not be guaranteed). What would be the significance? Is, for example, the difference between 1/2 wave and 1/8 wave the difference between recognizing Jupiter in the eyepiece, and being wowwed at the detail in its cloud bands?

I'm interested in everyone's thoughts, and do not presume opposing views as being attacks on each others competence. I see this as a practical exercise. It's not surprising that a perfectly matched set of optics would be ideal, so the question becomes picking the best solution among five:

(1) All new optics (expensive -- beyond budget for now!)

(2) Mix n' match

(3) Refurbish original optics (if possible; maybe also expensive?)

(4) Anyone know how to refigure the secondary?!

(5) Quit (why? we've come this far, and at least will have working mechanicals with the potential for improved optics later)




Joe,
I would strip the coatings off the original mirrors, chemically. I have seen mirrors with very bad coatings look like they were hopeless, yet when the coatings were removed the glass was perfect and when recoated, looked perfect as well. In my opinion the original optics has the best chance of giving the best image, but I would check the new ones as well.
If it was me I would sets the optics up in double pass autocollimation to test them. This is one of most sensitive test one can do and it is done on the complete system. Also there is nothing to measure. If the Ronchi lines are straight and/or the system nulls like a perfectly spherical mirror, the correction of the complete system is dead perfect. If not one can see exactly were the problems are.
Knowing that most people don't have a large optical flat to do double pass testing, then I would at least Foucault test the primary mirror. This will give one some insight to overall optical quality of the system and if can be optical corrected, well. In theory the primary should be a perfect sphere so it is a straight foward null test with a Focuault tester to do. In most cases the primary won't be a perfect sphere but will be a very weak ellipse. This is just a fact from rapid machine polishing used to make them but what is critical is that the figure is optically smooth. So no turned down edge or rough surface. A common error is what is known as "record grooving". The optical surface is rough will and looks like a grooves under the Foucualt test. Again this is caused by the high speed polishing of the surface. Luckily all this can be fixed by repolishing the surface on a pitch lap by hand. If the mirror has these errors then no amount of correcting the secondary is going to fix these problems until the primary is refigured. So the set of optics with the better primary and with it's matching secondary has a better chance of giving the better image.
As for the picture of 10" corrector being tested via interference against a 12" optical flat, the pattern of wiggly lines is were the Schmidt curve is it's deepest. What one wants to see is that the pattern forms a concentric ring around the corrector. If it is oval shaped or has any bumps then the corrector has astigmatism. If that is case then it's time for a new corrector. I've attached a close up picture. The pattern on the right side is different then the left from the astigmatism.
If you want to refigure the secondary, first you need to be sure that the primary is optically smooth and close to spherical and the corrector doesn't have any astigmatism. Then you jig up the optics just like how they are going be installed in the scope. You need to test the system by double pass autocollimation using a large optical flat. The light passes thru the system twice so any errors are doubled making for a very sensitive test. By the way this was the same method that Sky and Telescope used in 1989 article that looked at the optical quality of commerical SCT sold at that time. The secondary is not spherical as has been stated in the past. It is aspherical and depending on the residue errors in the corrector and primary, it is figured somewhere by an ellipse to a hyberbola to fully correct the system. You use a pitch lap with a peddle shaped pressed into it and slowing polish the secondary while testing every few minutes until the system shows straight ronchi lines and/or null like a spherical mirror. When that condition is meet, the system is perfect.

Happy Holidays,
- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Restoring a C8 After Purchase -- Update new [Re: DAVIDG]
      #5575517 - 12/17/12 10:58 AM Attachment (30 downloads)

Here is a picture of what the pitch lap would look like to figure the secondary. This one is much larger in diameter thou and was for a 6" convex surface I was working on. One for C-8 would only be 2" diameter.

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: DAVIDG]
      #5575725 - 12/17/12 01:26 PM

Wow, Dave; thanks! That's an impressive tome, something I can follow, but can not yet imagine doing myself. Here's my take on the situation:

It sounds as though if one has the tools and the skills, then not surprisingly, the optics of any telescope could be rebuilt. The one exception is corrector plates. Strictly speaking, they could be rebuilt, too, but it was Tom Johnson's genius in inventing a means to mass produce them that made Schmidt-Cassegrains practical. If the corrector is bad, we replace it. Mirrors, we (some of us!) can grind. (An aside: I've heard that the meniscus lens of a Maksutov is well within reach of a commited, determined amateur.)

The problem comes down to the time required to acquire the skills, the cash required to build an optical lab, or --Larry's approach-- the economics of working with what is affordable and available. Larry cleaned the corrector (he says his mild polish did not remove the coating, but only its top layer). He has since installed the mirrors from another scope (one with a broken corrector). Against an artificial star, he has rotated the components to optimize them to each other, however imperfect that may be. Next clear night, he'll star test it against a real star focused at infinity, and test it against known double stars to determine its wave fraction (I'm not sure how to call that; is it 1/2 wave, 1/4 wave, a lucky 1/8 wave, 1/1 wave (ugh!)). With any luck, we'll have a serviceable scope at an affordable price. If not, then we invent Plan B.

I like the idea of sending the original mirrors out to be stripped and assessed. Can anyone recommend a good lab?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5575739 - 12/17/12 01:38 PM

Quote:

The one exception is corrector plates.




I did find this page on manufacturing Schmidt correctors amusing, especially the part on using the vacuum pan method where a sheet of plate glass is used as the lid of a vacuum chamber and is deformed under vacuum into a catenary curve and the top side ground flat* so that when released it has the correct profile for a corrector plate.

What tickled me was their comment "Although the process seems a bit involved, - Schmidt Correctors are surprisingly easy to make."

Although they do go on to say "Once you have a large polishing machine, a vacuum chamber and a fair bit of experience!"

James

* Edit - I'm getting confused withe the master block process, in the vacuum pan method a spherical curve is ground into the top surface whilst deformed.


Edited by Masvingo (12/17/12 06:43 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5576105 - 12/17/12 05:40 PM

Interesting page, James. It seems to show a different process from the one Celestron used. I thought Celestron sucked the glass hard against a machined steel mold, then ground the opposite side flat. That was Tom Johnson's innovation for making correctors inexpensively.

Just received a Japanese (!) Meade Series 4000 f/6.3 focal reducer won on eBay. No one was bidding on it. Cost about half of a new Chinese, and is better. The box shows it was originally purchased from Hands On Optics, and was once priced at $80. Came with original bolt case and both end caps. Any idea how old it may be?


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5576136 - 12/17/12 06:00 PM

Schmdit corrector are actually easy to make. You don't need a vacuum chamber or anything like that. The tough part is finding someone who has a lathe to turn the vacuum pan which is nothing special. Just a thick piece of plate with a flat rim machined on it and a very slight depression machined in it. Once you have that it is fairly straight forward. The amount of vacuum required is very small. You can use your lungs to create it and one uses a spherometer to check the depth of the curve. The pan is filled with preboiled water to remove any gas from the water and you just suck out some of the water to pull a vacuum. You want to use water and not air because water is much less compressable so it supports the corrector while it is being fabricated. Also with water you don''t have to worry about changes in the air pressure changing the depth of the curve while your making it. Once the curve is at the correct depth you grind the corrector's surface with a premade convex tool which is made by classic mirror making methods until the complete surface of the corrector is fully ground. The surface is then polished. The vacuum released, the corrector is flipped over and rotated 90 degrees, vacuum pull again to set the correct depth and the back surface ground and polished. So 1/2 the correction is placed on each side of the corrector. This is done so one surface doesn't need to be optical flat or nearly so and also because the requirments for the quality of the corrector blank is greatly reduces because your going to work both surfaces. This is the classic vacuum pan method and it takes more time then what Celestron does with their Master block method but it will give the same results if not better, it just takes longer and in business time is money.
In the Celestron method the glass is sucked down against a glass disk that has the exact opposite Schmidt curve in it. The curve in the Master block is made by sucking it down against Schmidt corrector that was made using the classic vacuum pan method.


- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: DAVIDG]
      #5576170 - 12/17/12 06:18 PM

Pre-boiled water as the fluid for making the vacuum -- brilliant! I think of "air" with vacuums, and had not seen how air could have supported the grinding tool.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5576191 - 12/17/12 06:28 PM

Hi Joe

Tom Johnson's patent applications give a summary of the 'prior art' to his inventions and state that there were two existing methods for producing correctors:

1. The classical approach which was to grind the Schmidt curve directly into the face of a glass blank of sufficient thickness that it would not deform or bend under the temperature or pressure of the grinding operation. Progressively finer grits are used until the plate is ready for polishing. It is during the fine grinding phase that the figure is checked optically and those zones which are identified as being too high are worked down, this cycle of testing and reworking being repeated until an acceptable figure is achieved. These cycles of testing and reworking make the classical approach impractical for volume production.

2. The vacuum deformation technique, which was attributable to Bernhard Schmidt, who is credited with inventing the Schmidt corrector plate in 1931. Johnson's patent application was rather scathing of this method and suggested that it would be difficult to produce quality correctors from it due to the lack of any solid support for the plate whilst being ground and that any inhomogeneity in the glass would result in non-uniform bending. Again, this method was not suitable for mass production.

Johnson's master block patent solved these problems and, once the master block had been produced, enabled rapid, consistent production of plates. One of Johnson's patent applications, #3889431, suggests that high quality corrector plates can be made at a rate of 1 plate every 4 hours for each machine in use and that a single operator can easily handle as many as 12 machines after he has developed some skill.

The patent applications also mention an article, 'Study on the Fabrication of Aspherical Surfaces' by Sakurai and Shishido in Applied Optics in November 1963, which suggested that Schmidt corrector plates could be made by bending a thin glass plate over a mould having the inverse of the Schmidt curve and then grinding and polishing flat the other side of the blank. Johnson goes on to note that the article did not indicate how to bend the glass plate over the mould nor did it deal with other practicalities of implementation. It was these issues which Johnson solved and which, in part, lead to him being awarded the David Richardson Medal by the Optical Society of America in 1978, Johnson being one of only a few non-Ph.D. optical engineers to ever receive the honour.

Congratulations on the f6.3 reducer, sounds like a good buy. I'm sorry but I don't have any idea of the age, it would be interesting to know when they switched from Japan to China.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Masvingo]
      #5576273 - 12/17/12 07:24 PM

Quote:

The classical approach... was to grind the Schmidt curve directly into the face of a glass blank




Hard to picture how that is done. You're saying they took the optical equivalent of a router or Dremmel tool, and carved a circular rise into the glass? The process sounds similar to my whittling a corrector out of a block of wood, albeit with a lens grinding gizmo instead of a jack knife. Was the tool of significantly smaller diameter than the blank?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: orion61]
      #5576537 - 12/17/12 10:24 PM Attachment (27 downloads)

Lots of interesting chatter here, but we all know Cloudy Nighters love pictures, so let's return to the core of our epic tale. Larry had quite a battle with the salt-encrusted, steel-corroded-to-aluminum screws holding the focuser, but he emerged victorious. In his own words:

"I finally got the focus cap screws busted loose on it. I worked about 2 hrs getting the screws and the focus assembly out. There is an end screw that must not be twisted out because of the location and depth a regular tap will not work, we would have had to replace the whole focuser those cost $38.00! BUT, I got it.

"The screws I ordered that were suggested to me were the wrong size, so I had to reorder a new tap. Those C8s take 4/40 screws. I will be replacing them with Phillips style. The older ones I have seen all had that kind, not Allen. My Super sharp C8 has Phillips, and it is a year or so newer than yours. I think they just used whatever they had. The Hex screws are about 12 dollars shipped; the Phillips are 1/4 of that price!! If you really want hex, I will put those in for you.

"I really love working on these things."

Indeed, it shows, Larry.

Now, about those screws at four times the price: Hex, schmex. We're going with Phillips.

Edited by Joe Cepleur (12/17/12 10:34 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5576553 - 12/17/12 10:30 PM Attachment (24 downloads)

Another image of the focuser upon removal. See all that salt! Looks like it got tossed into the end of the production line at a pretzel factory. Amazing to see it removed intact. Larry has the necessary skills, patience, and passion for this sort of work. It's play for him!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5577367 - 12/18/12 02:03 PM

Quote:

Hard to picture how that is done. You're saying they took the optical equivalent of a router or Dremmel tool, and carved a circular rise into the glass? The process sounds similar to my whittling a corrector out of a block of wood, albeit with a lens grinding gizmo instead of a jack knife. Was the tool of significantly smaller diameter than the blank?




Well, maybe not quite as dramatic. Conventional techniques as used for producing mirrors, using laps and progressively finer abrasive pastes would be applied but concentrating on the areas where glass is required to be removed. I would guess that generally speaking a lap some degree smaller than the plate would be used. From what I've read it is important that most of this work is done with the glass blank that will be the corrector being rotated about its centre to keep the glass plate a perfect figure of revolution.

I guess that this would also be the method used to produce the master block in Johnson's method which would have an inverse of the desired Schmidt curve ground into it.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Update new [Re: Joe Cepleur]
      #5577375 - 12/18/12 02:06 PM

Quote:

Another image of the focuser upon removal. See all that salt! Looks like it got tossed into the end of the production line at a pretzel factory. Amazing to see it removed intact. Larry has the necessary skills, patience, and passion for this sort of work. It's play for him!




Yikes! Salt everywhere. Kudos to Larry for having the patience to get things free. I invariably get impatient, use too much force and then shear screws or worse!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Masvingo]
      #5578494 - 12/19/12 07:28 AM Attachment (21 downloads)

This innocent looking picture --if I understand correctly, which I may not-- hides the clue to what we anticipate as the only snag in the project. Here we're looking at the fork's cross arm, where it rotates about the mount's base. Larry reports that the bearings inside are broken. Best he can figure, after they froze from the corrosion, The Incredible Hulk tried to free them with brute force. The forks refused to rotate, but the base was willing to break. Note the corrosion in the axle:

Edited by Joe Cepleur (12/19/12 02:43 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #5578498 - 12/19/12 07:33 AM Attachment (19 downloads)

The break was not visible until Larry dissected the base for repair. There, lurking between the two motors, hidden inside the housing shown below, were bearings, once upon a time. Now, there's just rust! Too bad. If they hadn't been broken, this would have been nothing a nice, relaxing bath in penetrating oil wouldn't have relieved.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #5578503 - 12/19/12 07:38 AM Attachment (18 downloads)

With the story being presented somewhat out of order, this sounds strange. Didn't the motors run already? Didn't the forks turn? "Yes" and "yes," but apparently there is a difference between the forks spinning unburdened on the test bench and their actually carrying the weight of the tube, along with attached cameras, eyepieces, finders, and counterweights. It had all looked so close to pristine at first, as the image below shows:

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #5578515 - 12/19/12 08:02 AM Attachment (21 downloads)

One can hardly feign surprise, upon reconsidering the condition of the inside of this casting. No problem! Larry sourced the necessary replacement parts. He knew just whom to ask, after repairing scopes for so many years. (When I find his mention of his source in my email, I'll be glad to edit this to credit it. Cloudy Nighters will want to know where to call for parts!)

With the magic of PayPal, I slipped Larry a Ulysses S. Grant to cover the cost of the parts, and the project jumped forward again. While we always hate to see a scope unnecessarily parted out, it is comforting to know that parts are readily available for these old C8s. Margarita's original base will now add to the worldwide supply! It contains good gears, good motors, good castings... Larry will be free to swap in the best parts to prepare Margarita for her next forty years!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #5580351 - 12/20/12 10:12 AM Attachment (14 downloads)

Look what I found! Even better pictures of the bad bearings, or at least the housings around the bad bearings. A little too much salt on this Margarita, but Larry fixed it!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #5580357 - 12/20/12 10:14 AM Attachment (13 downloads)

A little blurry, but one can see the rust in the base's central hole.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Brian RisleyModerator
Carpal Tunnel
*****

Reged: 09/04/06

Loc: SW Florida
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #5582508 - 12/21/12 01:22 PM

Is that the metal or nylon RA Lock Plate? Looks like the metal version to me.
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Brian Risley]
      #5583739 - 12/22/12 09:06 AM

It is metal. Joe has a couple pics from through the scope
put together, it has been to cold and I have been too busy to get it completely finished I think some questiones will be answered by the shots.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: orion61]
      #5583753 - 12/22/12 09:17 AM

Looking forward to seeing the pictures.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Masvingo]
      #5584217 - 12/22/12 02:50 PM Attachment (54 downloads)

I have decided to just add a few pics since Joe is busy..
here is the subject as seen by naked eye
next is through the scope at prime focus
I then just used paint and blew a section of the emblem up to bring out more detail.
the little red check mark is the target
I was very pleased to see the in and out of focus defraction rings were very similar, I didn't have the camera or the OAG adapter cooled down so I got some distortion and flairing from the room temp camera at 2Degrees above zero, plus the wind was blowing about 20 mph.. needless to say I didn't waste a lot of time out there.
A 6mm eyepiece showed a pretty decent looking airy disk
and defraction ring.
I think we can say optically this experiment is a success.


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: orion61]
      #5584222 - 12/22/12 02:51 PM Attachment (40 downloads)

2nd

Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: orion61]
      #5584225 - 12/22/12 02:52 PM Attachment (37 downloads)

3rd

Post Extras: Print Post   Remind Me!   Notify Moderator  
Escher
Pooh-Bah
*****

Reged: 08/30/07

Loc: Fenton, MI
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: orion61]
      #5584305 - 12/22/12 03:55 PM

Looking great man! You really brought this one back from the brink... The proof is in the views, and these are looking good!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Escher]
      #5584333 - 12/22/12 04:30 PM

+1

Looking good!

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Masvingo]
      #5584483 - 12/22/12 06:27 PM

Thanks guys, I am so happy for the owner, The best part is I
havent even finished with the final alignment of the optical components! and there were some thermals from the Camera body and off axis guider being 70 degrees warmer than the scope.
This project kind of got blown up here and there was some
great tutorials from Dave, and if he ever gets to the Midwest I'd love to take one of his Newtonian Mirror making Classes.
This it was simply a fun thing trying to make " Am Albatross Fly again", without spending money on it.
The owner couldn't believe it when he saw these images.
I tried the origonal optics and they were not a great example of Celestrons work. That was surprising becaus I had found the old "Orange Celestron Pacific tubes to be exceedingly good for a commercial product, One can tell Mr. Johnson took quality control very sreiously.
If I can find my old Eyepiece projection adapter from my film days I'll try to take some Stellar shots for you.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Holland
Carpal Tunnel


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: orion61]
      #5585219 - 12/23/12 08:40 AM

Albatross, or (salty) Phoenix?

Great job, sir. Thanks to both for telling Magarita's story for us all to enjoy


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: orion61]
      #5585286 - 12/23/12 09:46 AM

Quote:

If I can find my old Eyepiece projection adapter from my film days I'll try to take some Stellar shots for you.




Please do, Larry, that would be great to see, if you can stand the cold - it looks rather icy there (but I guess a summer day to the folks in Alaska).

Keep up the good work, it's great to see a 'scope comin back to life!

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Ed Holland]
      #5585726 - 12/23/12 02:36 PM

Thanks Ed, You are a member I highly respect, and I admire your body of work, I knew this project would work out.
but even I didn't expect this quality of optics to result!
I was expecting at least moderate SA from the set. This just confirms my belief that Celestrons Corrector process
was exceedingly consistant. Or I just got LUCKY.
I need to thank the owner in trusting me through all the posts expressing certain failure in the project.
I truely love these scopes and I have made it my goal to
salvage all of them I can, Being disabled and unable to
work, referbing gives me a feeling of acomplishment that was nearly taken from me, the day that Old Gent ran over me with his car!
I have heard people say that these will never be worth anything.
The people who own one know differently.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: orion61]
      #5660047 - 02/03/13 02:01 PM

A quick update for the fans: This scope is not forgotten, but Larry and I have each had major distractions in our lives that edged us away from telescopes for a while. Larry reports that he is working on literally the scope's final polish. I suspect that, cosmetically, this scope will be better than new, with a combination of clean, shiny surfaces, and the patina and occasional scars of age.

Importantly, Larry took Margarita outside for a star test, and sent this report. Like many of us, he does not claim to be an expert star tester, yet can tell good from bad. Consider the state this scope was in when we started! I'm happy with the outcome:

"My Star tests show it to be of acceptable quality. All I have to compare it with is the Leo Henzl
C8 that was custom figured by Celestron for him. You will be happy with it."

When Leo Henzl was Vice President of Marketing at Celestron, he had his personal C8 built just as perfectly as perfect could be. Larry now has that scope. Mine is not as good (yours likely isn't either), but it's far better than the salt-encrusted mess it used to be! I'm looking forward to spotting eagles across the lake, and exploring the stars with this resurrected classic.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #5660150 - 02/03/13 02:56 PM

Thanks for the update, Joe. I'm looking forward to seeing pictures of Margarita in all her refurbished glory. Sounds like Larry has done a great job.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Masvingo]
      #5682608 - 02/15/13 11:44 PM

Larry and I spoke tonight to confirm the shipping address for sending Margarita home. I'm looking forward to first light, and shall of course post a report.

Larry had the scope under the stars in ideal seeing conditions last night. Saw many objects, did a star test. After owning and using many, many C8s, and refurbished thirty, Larry reports that this one is average, or maybe a touch above. "Average" is what one would expect, and with a C8, it's excellent! Weirdly, but most welcome, this one actually performs better with the replacement mirrors and original corrector. Early in the refurbishing, trials of the original mirrors showed they were astigmatic. So, whatever may have been lost in the matching of mirrors to corrector, more was gained by swapping in better mirrors. This vindicates Celestron's claim that their manufacturing was so precise that any combination of mirrors and corrector would work. Imagine this scope if it also had the matching corrector, but that had been broken in the scope that was thereby freed to donate the mirrors.

Shipping will be thrifty, and so slow. Good old U.S. Mail will bring Margarita home in about two weeks, but at blissfully low cost. When she arrives, we'll see you at the same Bat-time (a cloudy night for sure!), same Bat-channel!

Vintage Astro-Physics and Nippon Kogakus, Bah! Just think: I'm going to be the only guy in the world with an Orange Tube C8 that had been salt-encrusted in the air and waters of coastal Maine, only to be refurbished in Iowa by an inductee of the Iowa Rock and Roll Music Hall of Fame. Talk about seeing stars!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: orion61]
      #5799013 - 04/14/13 05:59 PM

Dig this! I woke my netbook from sleep for the first time in several months, and found this entry written but, I believe, never posted!

<><><><><>

Sorry to have dropped out of touch for so long. It's been nearly a week since Larry posted the most impressive pictures taken through my scope. Even if, with further tuning, it becomes no better than it already is, the scope will clearly be fine for low-power views of extended objects. It will be a fine, if bulky, birding scope (perfect for watching bald eagles from over a mile away!), and an entirely suitable companion as I continue to learn to find Messier objects. Whether it will resolve every last star deep in some globular cluster misses the point. As Larry so well describes, our goal was to make a truly useful scope out of a salt-encrusted classic. He has fixed it well. I'm happy with it already, yet it will be interesting to see the star test after Larry finishes tweaking the optics.

<><><><><>

Jumping to today, as of last week, Larry is shipping Margarita back to me. He was so proud of his work that I invited him to keep it for a while, so he could use it for plenty of observing sessions prior to shipping it home.

His tests show Margarita to be an average C8, or maybe a hair better. But, C8s are excellent! Nothing wrong with one being "average!"


Post Extras: Print Post   Remind Me!   Notify Moderator  
amicus sidera
Post Laureate
*****

Reged: 10/14/11

Loc: East of the Sun, West of the M...
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #5799050 - 04/14/13 06:31 PM

So, the Margarita will be returning home - excellent! It's been a long road; very glad you'll have it back soon.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: amicus sidera]
      #6002659 - 08/02/13 06:53 AM Attachment (16 downloads)

January 31, 2012 -- nineteen months have passed since this thread began, just over a year-and-a-half since Margarita entered my life, and I began the Quixotic quest to restore a venerable, salt-encrusted telescope. I'm delinquent in posting pictures, because I moved a month ago, at about the same time the scope arrived back from Larry. I had to place the poor scope into storage during the chaos, but have finally returned to see her with a camera. Sorry, no first light yet; but finally, first pix. Look back in this thread to see how trashed she was when Larry received her, and you will be suitably impressed.

I especially like how, in warning the shippers to handle with care, the box reads, "Scientific Instrument!"

Edited by Joe Cepleur (08/02/13 06:55 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #6002661 - 08/02/13 06:58 AM Attachment (15 downloads)

Double boxed!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #6002662 - 08/02/13 07:00 AM Attachment (12 downloads)

Not just any ordinary box, but a genuine Celestron shipping crate! Special thanks to Larry for loaning that. He may buy a hard case for his C8s, or I may ship this back to him empty, as promised. Hey; anyone have a C8 for Larry to fix? I'll ship you the crate!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #6002665 - 08/02/13 07:02 AM Attachment (15 downloads)

No question, everything is well protected in Celestron's crate. Good thing C8s are essentially unchanged in forty years. This old scope fits a much newer crate perfectly!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #6002666 - 08/02/13 07:04 AM Attachment (12 downloads)

There was even room inside for fragile accessories.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #6002670 - 08/02/13 07:06 AM Attachment (14 downloads)

The diagonal is a miracle of repair, if one looks back to its former cracked, broken state as shown earlier in this thread. We save everything we can in restoring classics!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Broken Base! new [Re: Joe Cepleur]
      #6002673 - 08/02/13 07:09 AM Attachment (13 downloads)

The finder looks pretty, but its optics could not be fully restored. But, can't waste a glorious orange tube, so here it is for posterity. Works well enough to sight objects, and so-so enough to warrant replacing. Still, a miracle, if one recalls the heap I shipped to Larry. Note the tender care with which the tube is wrapped to prevent further scratching!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002677 - 08/02/13 07:13 AM Attachment (13 downloads)

Such torment, showing accessories before the scope itself! This is the full experience, revealing everything in the order it was removed from the crate.

The erecting prism is clean. I suspect the salt-encrusters scarcely used it, and Larry cleaned it even better than it came to me.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002679 - 08/02/13 07:14 AM Attachment (18 downloads)

Finally! Isn't that one beautiful C8? Hard to believe the transformation!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002682 - 08/02/13 07:18 AM Attachment (15 downloads)

The lens cap did not fall off when I touched it, as it used to. It was snugged just right into the tube. Larry installed some Velcro strips that compress against the opening to hold it in place.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002685 - 08/02/13 07:19 AM Attachment (12 downloads)

Camera focused on correcter.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002686 - 08/02/13 07:20 AM Attachment (11 downloads)

Camera focused on primary.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002690 - 08/02/13 07:24 AM Attachment (13 downloads)

Larry polished the original orange paint, carefully removing its oxidized surface, but not a hair's depth more. The objective was refurbishing, not restoring. We wanted to show the scope in its weathered, used, scarred state, yet clean, so its wisdom and experience would be evident. Magnificent!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002693 - 08/02/13 07:26 AM Attachment (13 downloads)

Stately!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002694 - 08/02/13 07:27 AM Attachment (12 downloads)

Clean!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002696 - 08/02/13 07:29 AM Attachment (10 downloads)

All original! Well, almost. The forks and base are of the same vintage. We swapped 'em for the salty originals. Larry kept the salty forks to restore for another project. Love that original lens cap!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002703 - 08/02/13 07:40 AM Attachment (12 downloads)

Shucks! Gotta put her back into the crate, for safekeeping in storage a while longer. Note the original stickers. They are faded, perhaps from exposure to too much salt, but one reads, "Special Coatings."

Actually, the scope does have special coatings, but not the ones expected. Rather than recoat the original mirrors, Larry swapped them for a set of Starbrights from a newer scope with a broken corrector. Amazingly, the package works quite well, despite these optics not being a matched set from the factory. This speaks well to Celestron's quality control. Whatever the debate about how well this should work, it does, and far better than it did in its salty state. Maybe someday I'll restore the original mirrors. Truth is, Larry found some astigmatism in the originals, so this hybrid set may well be better anyway, even if that is not supposed to be theoretically possible. Larry was so proud of this refurbishing that I invited him to keep the scope and use it for a good while after the work was finished. It star tests well, at least as well as a typical C8, which is well indeed. My guess is that, whatever was lost in not having a matched set, was more than offset by Larry's meticulous aligning of the optics. This scope is surely better than a stock C8 in that regard.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002704 - 08/02/13 07:41 AM Attachment (12 downloads)

Family portrats of accessories.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002705 - 08/02/13 07:42 AM Attachment (10 downloads)

Pretty from all sides.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002708 - 08/02/13 07:43 AM Attachment (9 downloads)

Looking forward to everyone's comments. I promise to report again after my first light!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6002759 - 08/02/13 08:28 AM

Looking good Joe! Larry did a great job.

You have more willpower than me, I don't think I could have waited a month, house move or no house move!

Did you swap the serial number plate over to the replacement base?

Looking forward to hearing about first light.

James


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Masvingo]
      #6002876 - 08/02/13 10:01 AM

Quote:

You have more willpower than me, I don't think I could have waited a month, house move or no house move!




Thank you for the flattering appraisal. It was less "willpower" than a situation forced upon me.

Quote:

Did you swap the serial number plate over to the replacement base?




Excellent memory, James. Larry has the original serial number plate. He's going to remove it from the original base, or ship the hulk to me to remove it. I don't know whether to glue it to the new base alongside its original plate, or, breaking with Celestron's standard, to glue it to the tube, where it will never be separated again. Could also fasten it to the inside of the accessories case. Your vote?

Larry and I have become friends through the course of the scope's long refurbishing. The gods were with us on this odd odyssey. I got to champion setting an old, abused classic right in a time of my life when it was especially gratifying to see something improve steadily, and he was sustained by an opportunity to work at what he loved, at whatever pace was possible, through the complex saga of recovering literally from being a pedestrian who was run over by a car several years ago. Whatever value there is in having one more scope from our collective history ready for long service again, the experience of setting this corner of the world straight has been even more valuable to each of us.

Tim53, consider this scope your project as well. It's true that the introduction to Larry came through you and several others on the Forum. Still, the decision to mail it and money for its repair to a man who was a stranger to me at the time came 100%, and without fear, upon receiving your assurances that you knew Larry, and could vouch he was a good man. Others seconded that, but I had decided to send it to him immediately upon hearing from you. That makes Margarita Tinkey's cousin!


Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6003056 - 08/02/13 11:34 AM

All I can say is WOW!

That came out beautifully!

Kudos to you for having the desire to save it, and kudos to Larry for having the skills needed to do it!

-Tim


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Photographs new [Re: tim53]
      #6003460 - 08/02/13 04:14 PM

Thanks Tim, coming from you it is a great compliment, I'm trying to figure the correct way to get the original SN plate off, any suggestions??
For those that think you cant hand polish a corrector, as they say, the proof is in the pudding.
Another thing is, the mirror and secondary from one system can match up with another corrector just fine.
We may have gotten lucky??? But I have done this before.
The system Star tests very well! I have looked through
factory C8's that weren't as good!
Hey Joe, is there a way you could post some before after shots?
I very much prefer to referb a scope, making the best of what is there as opposed to sand and repainting.
At times you cant help it, I did hand mix and match the Orange and grey base paint to cover chips.
During this time, I had a Pulmonary Embolism that resulted in a heart attack, so I'm glad Joe has a lot of patience!!!
I'm saying this to let people know I don't normally take this much time to work on one.
You are a great guy and I think of you as a good friend!
It's kind of funny, I got fairly attached to that scope!
Everybody with the time, and likes FRUSTRATION, should do this. It is a rewarding experience. I think the hardest part was drilling and tapping the frozen/twisted corrector retaining ring screws out. The Aluminum cell is much softer
than the harder screws!
(I also gained a friend out of the deal)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: orion61]
      #6004097 - 08/02/13 11:01 PM

For before-and-after pictures, check the earlier pages of this thread. There are zillions of pix showing the scope in its former livery of salt and corrosion. The transformation is astounding. All that salt was insideous. It may not look like much, but it's a devil to clean.

The corrector ring that troubled Larry -- That's the reason I sent it to him! I knew I could not remove it without breaking the glass.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6004527 - 08/03/13 10:12 AM

In refurbishing Margarita, there was a lot of discussion (including by private message) about the risks of mixing one scope's mirrors with another's corrector, and also about the importance of smooth figure to all optical surfaces. From Larry's star tests and weeks of using the finished telescope, and from the photographs of the car posted earlier in this thread, it appears this Frankenscope works fine. This is in keeping with Larry's assertion that the matching of the mirrors was critical, because errors in the primary were corrected by tweaks to the secondary, but the correctors were actually surprisingly consistent.

One insightful question was whether polishing the corrector to remove haze and salt-crud would harm its figure, or even just its all-important smoothness. Cleaning was essential, but at what price, with what assurance of safety to the optics? The risk was that because optical coatings are just a few molecules thick and because of how they work, removing even a layer or two could change them from helping to hurting the image. Larry used NOVUS Plastic Polish. It is intended to clean soft plastics that have been weathered from years outside. It is, apparently, insufficiently gritty to alter the figure of glass, and even gentle enough to somehow clean away deposits without noticeably harming the smoothness, at least at the eyepiece. Can't vouch for what a trained eye might see on the test stand, but as a practical matter of cleaning a scope as apparently trashed as Margarita had been, NOVUS seems to have worked well.

Please understand that I am not endorsing NOVUS as an everyday cleaner for telescope optics. I don't know enough about it. I'm only saying that, on a scope as needy as Margarita, it appears to have helped far more than it may have hurt.

Edited by Joe Cepleur (08/03/13 10:24 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6004751 - 08/03/13 12:28 PM

A good point and when cleaning anything optical I always start with Filtered Blue Windex. I would not suggest that anyone start using anything with a Cleaning/abrasive base.
In this case NOTHING else worked. Most cases corrector spots hurt "feelings" more than views. We also may have gotten Lucky mixing optics from the 90's and 70's, it does make a statement to the fine and unchanging quality control
process from Celestron.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: orion61]
      #6004848 - 08/03/13 01:47 PM

Quote:

Filtered Blue Windex




Filtered through what? It is as simple as using coffee filters?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6004876 - 08/03/13 02:06 PM

Looking back through this thread, I found details of exactly how Larry cleaned the corrector. It wasn't just off-the-shelf NOVUS polish. Turns out he uses NOVUS as a base for a custom slurry. For the life of me, I can see the post on Page 9, but can't find it with the site's weak search features to allow linking to it, so I've copied it here. The picture is linked from Larry's post:

Quote:

I use the Novus system and I add different percentages of Cerium Oxides, Cerium NANO Oxide, and fine powdered Aluminum Oxide. mixed in as my own "slurry recipe" tried and perfected through the years from my first days working in an Optical lab, grinding and polishing lenses.
here is the "after" result of the the carefull hand polishing, I actually use a converted lensometer to measure the aspheric gradient power so not to change it. I marked the "Plano" side in different colored dry erase marker showing the gradient steps of power
There is some dust as I sat it onto the empty OTA.
The lighter and darker uneven area isn't the coarings but the Ultra Black paint drying in thicker areas.. You can see the difference from the pictures on the top of the page showing it as a nearly Charcoal powder look.
I'm very happy with it.






Post Extras: Print Post   Remind Me!   Notify Moderator  
Jim Curry
Pooh-Bah
*****

Reged: 10/29/07

Loc: STL
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6004950 - 08/03/13 02:58 PM

Whew, what a journey. Now you've got some aperture!

Jim


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Jim Curry]
      #6005048 - 08/03/13 03:41 PM

Jim, how wonderful to hear from you! I miss you. The club misses you. Hope things are well at your new digs. Can you see the sky from your new home in town? For astronomy, it was hard to beat your former spread far out in the country.

The neat thing about my newfound aperture is that I can lift it, and even fit it into a car! It's a compact imitation of a seven-foot long refractor. Not quite the same, I know, but ever so manageable. Can't see anything it I can't get the scope to the viewing site. An orange tube C8 isn't just a cool classic; it's a fine everyday workhorse for the budding astronomer. I'm going to use it to find again the Leo Trio you showed me!


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6005317 - 08/03/13 08:17 PM

Quote:

Quote:

Filtered Blue Windex




Filtered through what? It is as simple as using coffee filters?



Actually yes I use 3 Mr Coffee filters and slowly get my cleaner.
Dr Clays mix is as good or better, just remember not to use
tap water, there are a lot of minerals in there.
Distilled water is best, just don't try drinking it by mistake instead of bottled drinking water! YUUUK!
Glad you hooked up with an old buddy Jon, oops Joe


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6006208 - 08/04/13 03:30 PM

Quote:

Larry has the original serial number plate. He's going to remove it from the original base, or ship the hulk to me to remove it. I don't know whether to glue it to the new base alongside its original plate, or, breaking with Celestron's standard, to glue it to the tube, where it will never be separated again. Could also fasten it to the inside of the accessories case. Your vote?




I'd go for the tube, that way the history of both parts is on the 'scope and each plate is on the relevant part. For C8s that were sold as an ota only Celetron did put the serial number plate on the tube so there would be some sort of precedent.

Looking forward to your first light report, and great job again Larry .
I can imagine that was quite a job drilling the corrector plate screws out.


(Edited to correct typo)

Edited by Masvingo (08/05/13 03:20 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Photographs new [Re: Masvingo]
      #6006318 - 08/04/13 05:29 PM

I tried Floss and heat to get the original tag off, any Ideas?? Even getting the edges up by a razor blade has bent the 1mm I have lifted it. I dont want to wreck it, I know it means a great deal to the owner to have it intact.
BOY what ever they stuck it on with was meant to last a life time!!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Masvingo]
      #6006879 - 08/05/13 12:10 AM

Masvingo, that's interesting -- Where on the tube did Celestron put the serial number plates? Is it easy to describe exactly, or would you have a photograph?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6007000 - 08/05/13 03:18 AM

Joe, the only one I've seen a pic of is the very first ota that was sold separately and was previously owned by Charles Cunningham (greedyshark) before Celestron reacquired it. A couple of pics can be seen on this thread which show the plate was fixed to the tube just behing the corrector cell on the left side as you stand at the rear with the plate facing the rear.

The first pic in that thread shows a long shot of the scope, but if you go through all the pages you'll come to a closer shot which shows the orientation of the label better.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Photographs new [Re: orion61]
      #6007004 - 08/05/13 03:26 AM

Quote:

I tried Floss and heat to get the original tag off, any Ideas??




Sorry, no, heat was what I would have tried. It may be quite a laborious process as the base will act as quite a good heat sink and you don't want to use too much heat as otherwise the paint will burn. It might be a case of just being very slow, trying to get hot air in between the base and the plate if you can get a corner raised and doing it inch by inch (or more likely millimetre by millimetre).

I would guess that any solvent sufficiently string to dissolve the glue would probably remove the paint on the label as well.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Masvingo]
      #6007177 - 08/05/13 08:01 AM

Thanks, Masvingo;

I hope linking to pictures referred to in other threads is allowed. There's just no other good way to identify them. I wish there were an easy way to find and link to individual posts, rather than entire pages. Following your link, on the first page, I found this picture:



The larger scope on the upper right shows the label clearly, albeit far too small to read. Also found this close-up, from lower on the same first page. Its resolution is just high enough to show the label's orientation. This image also shows the separate label on the mount:



The label we are trying to remove is on a totally trashed base. Hate to say it, but it was so corroded from all that salt that it's beyond hope (although, weirdly, Larry did get I think both of those motors working, and he salvaged the forks for another project). Maybe, as a last resort, heat could be applied to the base with a blowtorch. Then, as the heat migrated under the label, the glue may release -- if the label did not first become a tragically lost, scorched mess!

Edited by Joe Cepleur (08/05/13 09:58 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Masvingo
scholastic sledgehammer
*****

Reged: 01/10/12

Loc: Ayrshire, Scotland
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6007221 - 08/05/13 08:39 AM

Yes, those were the two pics I was thinking of.

A scorched mess would be my worry with a blowtorch, or even a heat gun. I would star with a hair dryer but it may be quite a long, slow job. Maybe a heat gun applied from inside the base would work without getting the tag so hot that the paint would burn?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: Masvingo]
      #6007309 - 08/05/13 09:53 AM

Since the base is trashed anyway, how about heating it submerged in a pan of water? That would get the heat through everything evenly, and since it could not be heated above boiling, may prevent damage to the label. With a thermometer in the pan, it should also be fairly easy to control a slow, gentle rise in temperature. Maybe a fairly low, even temperature would work after a long time. It not, edge the temperature up a bit, and wait.

Edited by Joe Cepleur (08/05/13 09:56 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6007461 - 08/05/13 11:46 AM

I'll have to get out my Stainless Turkey cooker and give it a try.
I have tried everything else, I did try a small torch on the inside base. I went through 3 of the small fuel refills! it got good and hot but the glue still held fast,
All the years sitting outside has cured out much of any tack from the glue and it is now nearly like an Epoxy holding it fast.
Perhaps submerging it and running a rolling boil for awhile
will help.
If this doesn't work I'm out of ideas. And yes amazingly I did get both motors to work, but the Aluminum base is hopelessly corroded and pitted on the thrust surfaces.
The bearings are so corroded in they would need to be drilled out, I don't have any Machining equipment big enough to do this. The pitting is such I'm afraid the bearing walls would just crack.
Lovely Display by the way!! Love the old Sandcast two tone C8!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: orion61]
      #6007475 - 08/05/13 11:56 AM

Quote:

I'll have to get out my Stainless Turkey cooker and give it a try.




You're in good company. It's said that, in the early days of Hewlett-Packard, the founders used to bake enamel finishes onto steel cases in their wives' ovens, a timeshare between baking break and Sunday dinner.


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6008309 - 08/05/13 08:44 PM

Hey I still do that, Makes for a HARD high smooth glossy finish..
Also a very stinky house for a couple hours..
The last 2 times I've done it I was told it better be the LAST time!
I haven't had the guts to try it again.


Post Extras: Print Post   Remind Me!   Notify Moderator  
greju
Carpal Tunnel
*****

Reged: 10/13/05

Re: Restoring a C8 After Purchase -- Photographs new [Re: orion61]
      #6008391 - 08/05/13 09:27 PM Attachment (8 downloads)

"Love the old Sandcast two tone C8!"

And the tri-colored ones are nice too.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Restoring a C8 After Purchase -- Photographs new [Re: greju]
      #6009675 - 08/06/13 03:08 PM

Yeah; the tri-tones are exceptionally gorgeous. Never understood why Celestron went to only two-tone, even though I'm still a big fan of them. Maybe plenty good looking, but less costly to paint.

I tend to be an opportunistic shopper. I'm unlikely to actively seek a sandcast, but I'd buy one if I stumbled upon one at the right price. As it is, I have Margarita, which found me through a member of my astronomy club, and also another similar C8 of the same vintage and color scheme, but that one came to me clean.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Live_Steam_Mad
sage


Reged: 07/24/07

Loc: Moss Bank, St.Helens, England
Re: Restoring a C8 After Purchase -- Photographs new [Re: Joe Cepleur]
      #6486203 - 04/24/14 06:01 PM

Could we have a description of just how the original corrector bolts were drilled out ? What exact tools (and sizes / types) were used?

Best Regards,

Alistair G.


Post Extras: Print Post   Remind Me!   Notify Moderator  
orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Restoring a C8 After Purchase -- Photographs new [Re: Live_Steam_Mad]
      #6486496 - 04/24/14 08:36 PM

I have all that information in a notebook and unfortunately I moved and the notebook is???
I will tell you it was a very difficult thing to do because the screws are hard Steel and the corrector front cell is soft aluminum. The screws must be ground flat then use a sharply pointed Chisel to put a dimple in the screw, then use a small bit to start the hole, or a drill press.
Otherwise the bit will slide off the screw and drill into
the cell.
You may be able to grind the screws off the corrector locking ring then remove the ring leaving 1/8th or so
screw sticking out. You may be able to get a small Vise Grip on the screw to back it out. Or possibly a small set of easy outs. If you have to drill them out you will have to tal new threads in it. They are not Metric like the mew Celestrons are.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Geo31
Carpal Tunnel
*****

Reged: 01/28/13

Loc: Kingwood, TX
Re: Restoring a C8 After Purchase -- Photographs new [Re: orion61]
      #6489868 - 04/26/14 01:20 PM

I would NOT use a grinder on those bolts. Besides risking the grinder slipping, I would not want to risk the hot bits of metal coming off the grinder damaging the glass.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | (show all)


Extra information
23 registered and 8 anonymous users are browsing this forum.

Moderator:  Rich (RLTYS), Brian Risley 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 9807

Jump to