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Need some advice on ~restoring my new/old C8

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#1 Thomas Parr

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Posted 04 February 2013 - 11:16 PM

Well I stepped in it. I went to look at C8 from about 1980 because my fiance really likes astronomy but has never had a telescope (know nothing about telescopes... yet so apologies if I use the wrong terminology). He had posted it at $200, but while we were there we were unable to get an image in the eyepiece and he just said. "Look, take it, if you get it to work, think about paying me something, if you don't then do me a favor and just get rid of it."

I took him up on it and now I have this beast. Tripod, wedge, motor controls and all. I need some advice refurbishing it and fixing some of its... personality.
-There is a light crease in the tube. My reading of the forums indicates this is not a problem. Other opinions?
-There is a chip in the reflector due to an oversize screw. This seems to be very common for this scope and most people say it isn't a problem or it is easily fixed with some black paint.
-I don't get an image. I am assuming this means the collimator needs adjustment.

These three seem like a good place to start. I will come back and post with more questions if I conquer these problems.

Images as requested
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Just the scope on the bracket

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Light crease on tube

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Chip in top of mirror, about the size of dime.

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#2 tim53

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Posted 04 February 2013 - 11:39 PM

pics?

We should be able to help. In addition to a number of us here who've had these puppies apart, you should be able to find all kinds of instructions via an internet search.

I restored an early orange tube here: http://www.cloudynig...3669709/page...

best, and welcome to Cloudy Nights!
-Tim.

#3 Joe Cepleur

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Posted 04 February 2013 - 11:43 PM

Welcome, Thomas Parr. Glad you stepped in it!

Can you post pictures of your scope? The C8 has a long history, with many different models.

Crease could be a problem if it is big enough to misalign the tube. For now, let's assume it's just (or largely) cosmetic.

Chipped mirror from a screw? For a free scope, not the end of your world. Paint it out.

Can't focus? Hmmm.... Gotta confess, a lot of folks will know more than me, but....

Is the diagonal missing? The eyepiece does not fit directly into the back of the scope. Instead, a kind of elbow with a mirror fits there. The eyepiece then fits in the elbow. This allows you to relax and look down when the scope is pointed sharply up. Without this elbow, the scope is missing maybe five inches of its length, and so will not focus.

Another idea: Have you been patient with the focuser? There are many turns lock to lock. Try looking at things at a variety of distances, even as close as 15 feet, to see if it focuses anywhere.

Still other ideas: Is it possible that the force that chipped the mirror also misaligned it? Is the eyepiece junk? Is the corrector reversed? The colimation whacked?

I'm somewhat of a wannabe, but fear not; the true scope surgeons will be along shortly!

#4 Datapanic

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Posted 04 February 2013 - 11:44 PM

Sounds to me like you got a good deal on it. Maybe that oversized screw is still in there and preventing the mirror from moving to focus. Like Tim said, you have a lot of resources here. Welcome to Cloudy Nights Classics!

#5 bob midiri

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Posted 04 February 2013 - 11:51 PM

Thomas first welcome to Cloudy Nights and the Classic Forum. There are a lot of very experienced people here who can help. Two things: First as others have stated, please post pictures. SECOND: there is nothing like hands on help especially for somebody new to the hobby. Check and see if there is a local astronomy club, there will be members that would be willing to help you, as a number of people own similiar scopes to yours. The Orange C8 is a great scope and I am sure you will be up and runing in no time. Bob

#6 Thomas Parr

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Posted 05 February 2013 - 12:37 AM

Diagonal is there, eyepiece is a Galileo 25mm, I don't know if that is quality or not.

#7 albert1

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Posted 05 February 2013 - 04:00 AM

Okay good, diagonal and eyepiece. Have you tried racking the focuser all the way in and out like Joe suggested? Like Dan said, make sure that oversize screw is out of there and nothing is preventing the mirror from moving. Don't force anything. Looks like somebody had the corrector (front clear glass) off. The orientation of the serial number is not correct. Don't worry about that yet. Lets get this thing to focus.

Welcome to CN Tom.

#8 Joe Cepleur

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Posted 05 February 2013 - 08:55 AM

There was no picture when I first responded. Seeing the scope now, you didn't "step in it." You got lucky! This can be fixed, and is well worth fixing.

Zooming in, do I see a blurry, retrofitted electrical cord? If so, Job 1 is assuring it's wired correctly. Not my specialty, but the local electro-experts will doubtless chime in soon.

#9 orion61

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Posted 05 February 2013 - 09:06 AM

Has the over sized screw been taken out?
you may be hitting it stopping the mirror from from reaching
proper focus.

#10 DAVIDG

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Posted 05 February 2013 - 09:30 AM

To remove most if not all of the dent without damaging the paint, get a short section of 2" x 10" about a foot long. Draw an arc on it the same diameter as the tube. Cut this out with jigsaw or band saw, so now you have two pieces of wood, one convex and one concave. You place the convex piece on the inside of tube and concave on the outside, so they are over the dent. Use a C-clamp and clamp down on the two piece of wood. This will push the dent out and reform the metal without damaging the paint. You'll need to work the dent out starting at one end and working toward the other and doing it a couple of times.
You might not have deep enough C-clamps to reach well into the tube. If that is the case you can use a hammer to tap on the piece of wood inside of the tube or better yet if you can fully remove the tube, so you can place two pieces of addition wood or metal bars over the wooden forms that stick out the end of the tube and clamp down on them to squeeze down on the wooden forms.
As a teenager I worked restoring pipe organs and we used this technique to repair the pipes. I've used it on a number telescope tubes include Celestrons and if you take your time and the dent isn't too bad, you can remove the dent so well that it difficult to see were the area was damaged.

- Dave

#11 rmollise

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Posted 05 February 2013 - 09:48 AM

Well I stepped in it. I went to look at C8 from about 1980 because my fiance really likes astronomy but has never had a telescope (know nothing about telescopes... yet so apologies if I use the wrong terminology). He had posted it at $200, but while we were there we were unable to get an image in the eyepiece and he just said. "Look, take it, if you get it to work, think about paying me something, if you don't then do me a favor and just get rid of it."

I took him up on it and now I have this beast. Tripod, wedge, motor controls and all. I need some advice refurbishing it and fixing some of its... personality.
-There is a light crease in the tube. My reading of the forums indicates this is not a problem. Other opinions?
-There is a chip in the reflector due to an oversize screw. This seems to be very common for this scope and most people say it isn't a problem or it is easily fixed with some black paint.
-I don't get an image. I am assuming this means the collimator needs adjustment.

These three seem like a good place to start. I will come back and post with more questions if I conquer these problems.


Neither the crease nor the chip in the mirror (it's in the big mirror at the back of the tube, right?) will do any harm. I would not try to fix either thing.

Do remove the offending screw.

What do you mean by "I don't get an image"? Of what? How are you trying?

#12 Thomas Parr

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Posted 05 February 2013 - 02:45 PM

Thanks for all the great advice so far!
By not getting an image I mean that I don't get an image looking through the eyepiece when focusing on things near (across the street) or far (night sky). If I pull the eyepiece and look down into the diagonal I can see my eye. If I pull the diagonal and look up the tube I can still see my eye. If I put something in the field of the primary reflector (e.g. my finger), it doesn't show up on the secondary... still just my eye.

Does that make my statement clearer?

#13 Masvingo

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Posted 05 February 2013 - 03:56 PM

Zooming in, do I see a blurry, retrofitted electrical cord? If so, Job 1 is assuring it's wired correctly. Not my specialty, but the local electro-experts will doubtless chime in soon.


If you are referring to the cord bundled up near the R A slow motion knob I think it might be the lead for the Declination motor - there appears to be a declination motor fitted under the fork arm and the cord appears to have a 12v connector on one end. Looks like the o-ring from the motor to the Dec knob is missing though.

It also has a piggyback camera mount which is nice.

#14 Geo.

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Posted 06 February 2013 - 11:11 AM

Actually, the collimation looks pretty good. May not be spot on but it's not far off. In the photo I can see the rear port opening in the secondary's refection so it's close. The optics look good and this may be all the telescope anyone ever needs.

The finder is a pretty rare 40mm (?). If so, it's a collectors' item and might bring $100.

The tube is aluminum, which stretches when dented. I wouldn't fool with it. A proper fix is best done buy a bodyman who works on Ferraris, old Lotus racecars, etc. It involves using torch to shrink the tube back to its proper shape. Hardly worth the cost when you can get a straight used tube for $50.

The mount is serviceable. If the oddball power cord is missing Hands-On-Optics stocks them for about $20. You have to look in their used scopes section for the cord. Gary told me he has them made up in 50-100 unit lots.

These were intended to be used on a tripod and equatorial wedge. The OEM was the locked triangle tripod. These go in the $75-100 range depending on condition, wedges are about the same. Although, just about any Celestron Schmidt tripod will work. The cheapest solution is a Celestar wedgepod. These have limited adjustability, but trade about $75 and get you both the tripod and wedge, as the name implies.

I have tripods and wedges or wedgepods available. If you're interested send me a personal message.

#15 DAVIDG

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Posted 06 February 2013 - 11:55 AM

Having refigured the optics in a number of SCT, I believe your collimation way off. When I look at the picture of the front of your scope, the label for the serial number on the secondary has been rotated out of position. Usually when they leave the factory the label is horizontal. When the scope got damaged the cell may have become loose and rotated. Also while the crease dent doesn't look bad, it is long and the metal distorted enough that the corrector cell may not be square to the primary cell. In the picture showing the crease, it looks like the left side of the corrector cell is tilting inward which would throw the collimation off and maybe by enough that the light is no longer going the down the baffle tube.
An easy way to check the rough collimation is to stand about 4 feet back from the front of the scope and look down into the front of the corrector. You'll see the reflection of the secondary mirror in the primary. Position yourself so the secondary cell is in the middle of the primary. You'll see the reflection of the secondary mirror in the primary. If the reflection is off to the side, the collimation is way off.

- Dave

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#16 J. Barnes

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Posted 06 February 2013 - 12:50 PM

My guess is one of the previous owners may have removed the corrector in an attempt to push out the dent. They may have put the corrector back in the rotated fashion it is in now. That may explain some of your problems. I defer to Uncle Rod.

#17 Pitter

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Posted 06 February 2013 - 02:53 PM

Like Rod said earlier, leave the dent and mirror chip alone. These are robust telescopes. They do however need to be properly collimated..."ALL THE TIME". Even badly collimated SCT's will usually give a terrestrial view. You may just need to find the focus sweet spot. Also even with a 25 mm eyepiece, across the road may be too close for good focus. Try an object further away. Here is a good link to help you take the telescope apart. It explains in simple detail. Once you have properly aligned the front corrector and the mirrors everything should be normal.

LINK:
http://www.astronomyasylum.com/c8.html

#18 Thomas Parr

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Posted 06 February 2013 - 09:27 PM

DavidG - Yep, I get something like the righthand image. Collimation is off.
JBarnes - I would agree with that considering one of the retaining screws is snapped off in the hole. I pulled the corrector last night to make it horizontal (baby steps).
Geo - it is the 40mm finder. I think i have most of the accessories I need. I added a few photos above of the whole kit&caboodle.
Masvingo-I took a closeup of that cable because I am not sure what that is. Does the picture above help?

#19 Masvingo

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Posted 07 February 2013 - 03:28 AM

Hi Thomas

I took a closeup of that cable because I am not sure what that is. Does the picture above help?


Yes, it does, thanks. That's the accessoery declination drive motor sold by Celestron, the should be a belt or o-ring from the white pulley up to the black declination slow motion knob above, on some of the declination motor kits the black knob was replaced with a grooved pulley as well, I'm not sure quite what the Celestron version used.

I think the declination motor used 12v dc whereas the right ascension drive motors in the base use 110v ac.

Cool - I see you also have two of the Celestron drive correctors, your find gets better and better! This should control both the declination motor and enable the speed of the RA drive motors to be aried slighly for precise trcking, it looks like a previous owner was into astro photography. The lead from the declination motor should plug in to the drive corrector somewhere.

I think you dd well with this find - enjoy!

James






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