notBert Loc: Ft. Collins, Colorado

In 1997 I bought a Celestron C-5 Schmidt-Cassegrain telescope. Recently I noticed the corrector lens has some internal “fog” ( see foto) and have contacted Celestron for instructions to demount the corrector as I have followed the instructions in the original Owner’s Manual p.25, but after removing the retainer ring, etc. the corrector seems to be cemented to two narrow flanges in the tube (see foto).
Tech support at Celestron replied to my Help request:
“Good morning,
Thank you for contacting Celestron Technical Support.
The corrector is not cemented in, it is merely stuck with age. It has been in place for 45 [sic] years!
It may be necessary to gently pry on the edge of the corrector with a thin blade to pop it loose.
Good luck!
Celestron Technical Support”

My reply was I had tried prying most gently, as the corrector is thin, to no avail. And I would appreciate a technique that did not involve “good luck”
My questions are:
1. Have any Celestron, or other, owners run into a similar problem trying to remove the corrector lens?
2. Did gently prying “pop it loose”?
3. I also tried seeping isopropyl alcohol around the edge of the collector but capillary action did not draw it in?
4. Any suggestion appreciated. TIA

DougS Loc: Central Arkansas

You may try to wrap the OUTSIDE BARREL in a heating pad (or similar method for causing heat related expansion) for a SHORT period, to hopefully cause the outside to expand but before the glass expands. Keep the glass cool. Quickly pry then. Good luck!

JBRIII

If worse comes to worse, try a little solvent, maybe acetone, let it get pulled in by capillary action. At work tape which would not stick to something at the start, years latter would be impossible to remove. They may have had a band of something to cushin (misspelt I know) the contact between the mirror and glass, now just a sticky mess or worse.

Try Cloudy Nights website for advice, also on cleaning, especially if its mold.

alberio Loc: Casa Grande AZ

I've never seen a corrector plate cemented in on a Celestron SCT. I have had to use a plastic pry tool to gently pry sideways on the edge of the plate in several places, sometimes repeatedly until it comes loose. First mark the plate orientation with the OTA housing. Then you must carefully lift it and pay close attention to the paper/cardboard shims under the plate and reinstall exactly in the positions they were in. There are also centering shims in some scopes. If you get the shims wrong the plate might have unnecessary stress and optical alignment causing a degradation of image.

tony85629 Loc: Sahuarita, Az

Contact STARIZONA. Thy are Celestron experts and very friendly and helpful. 520 292-5010

alberio Loc: Casa Grande AZ

Absolutely recommend Starizona, I've known Dean for many years and he is responsible for getting me hooked on this hobby.