[Inspiring thread for a question I keep forgetting to ask]
I have a Celestron spotting scope which otherwise has high quality optics, but a thumbscrew fell into it a few years back and scratched up the mirror pretty badly, and my attempts to get the sucker out have failed. Who might be able and willing to extract the offending object and polish the mirror for me?
Possibly contact the astronomy dept. of the nearest collage abd ask them? Maybe there’s an astronomy club in your area? Go to the library or on line and check Sky and Telescope magazine for the ads?
I have a C90, is that what yours is?
With luck the mirror will only have had the aluminium reflecting layer scratched. This can be re-applied. Actual scratches to the glass would be more expensive to fix than the scope, or at least the mirror, is worth. The coating is applied in a vacuum chamber, and is a common procedure - places that do custom optics will be able to do it. University physics departments often have the capability, although it may depend upon their research interests.
Have you contacted Celestron? They may be able to help or direct you. Any camera repair place should be able help too. They should be comfortable disassembling the scope. They may not be familiar with re-coating the mirror, but with a bit of direction it should possible to sort out…
Don’t expect much help from Celestron. I called them a few years ago about repairing a NexStar 8 with a broken primary mirror. They said they don’t do that, and that my only option was to replace the telescope. They wouldn’t even sell the OTA by itself, only the complete package (so I’d have to buy an extra tripod, tracking electronics, etc.).
Yep, C90.
Guess I’ll make some phone calls Monday.
Your best bet is probably an amateur astronomy club. Many of the members will have made their own scope, and if they can’t help you, they’ll know who can.
That is really bad. My hazy memory is that the mirror and the corrector plate are matched, so you need both, and the alignment isn’t trivial - the corrector needs to be fitted with exactly the correct orientation relative to the primary mirror and is precisely shimmed - so it really is a factory job to replace. But Celestron used to sell the OTA as a separate item years ago. Heck owners of C-14s used to use them as tracker scopes.