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Equipment Discussions >> Classic Telescopes

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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.


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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?


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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.

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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


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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.


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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


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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?


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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 (50 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)


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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 (40 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)


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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 (31 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)


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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 (27 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)


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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 (34 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)


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase [Re: Joe Cepleur]
      #5059189 - 02/06/12 08:20 PM Attachment (40 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)


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase [Re: Joe Cepleur]
      #5059190 - 02/06/12 08:21 PM Attachment (41 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)


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase [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)


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase [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)


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase [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)


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase [Re: Joe Cepleur]
      #5059203 - 02/06/12 08:23 PM Attachment (33 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)


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase [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)


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: Fixing a C8 After Purchase [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?


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