Hi,

I recently purchased a vintage (orange tube) C90. The telescope arrived with a loose light baffel in the OTA and thanks to some great advice from this forum, I was able to repair the problem. I later contacted Celestron's Technical Support with a question about the optical back threading, and they were not able to answer my questions about the vintage C90. I then realized how little on-line information is available regarding the orange tube Celestron C series telescopes. I decided to create a webpage to consolidate what information I found and currently I have a first draft on-line. This web page documents what I have learned regarding spare parts, manuals, and simple repair procedures. I have also included basic information about optical aberration and the MAK optical system. I hope this is information that can be of use to other C90 owners:

http://www.astronomyasylum.com/c90.html

A related issue is that I have recently constructed a homebuilt GoTo GEM for the C90; if anyone is interested, a post on this mount can be found on the ATM Forums page.

Bill