9.25" Celestron SCT with a broken corrector lens!

[SthBohemia]

Umpteen years ago I purchased the above for a pitance as I was after the Celestron fork and the CPC fork assembly! Rather than have the 9.25" sitting around gathering dust for another eternity I am considering making a spider to support the secondary and using the scope as a terrestrial telephoto lens. There must be others that have tried this approach to an otherwise useless optical assembly! Would be interested in hearing from them and results obtained.....

Any other suggestions regarding what to do with the broken OTA welcome 🙂

 

Cheers Rob.

[Cosmic Geoff]

Somwehere on this forum I recently saw a link to a company that supplies replacement corrector lenses for these SCTs.

If you do as you suggest the assembly will suffer from the aberrations the corrector plate is supposed to correct.

[Nik271]

From what I understand you want to replace the corrector plate with spider? I don't think this will help at all, the SCT have spherical mirrors and the corrector plays a key role to decrease the spherical abberation. Without it the scope will be crippled, I don't expect you will get sharp images. It may be better to try to glue the corrector plate, in the same way people glue cracked car windscreens. A crack, even a big one will not affect the image very much provided the rest of the plate is holding up. 

Edited July 6, 2022 by Nik271

[SthBohemia]

7 minutes ago, Nik271 said:

From what I understand you want to replace the corrector plate with spider? I don't think this will help at all, the SCT have spherical mirrors and the corrector plays a key role to decrease the spherical abberation. Without it the scope will be crippled, I don't expect you will get sharp images. It may be better to try to glue the corrector plate, in the same way people glue cracked car windscreens. A crack, even a big one will not affect the image very much provided the rest of the plate is holding up. 

Hi Nik. I have no intention of using the scope as it was intended for night use. I am curious as to how badly the abberations would be using it as a telephoto lens for terrestrial photography! The obvious answer is to try it and see 🙂

It has crossed my mind to use some E6000 glue and attempt repairs of the plate on a flat lathe bed, masking off the badly shattered edge of impact. At the very least the scope would perform reasonably for terrestrial use as 70% of the plate is in 1 piece. I have the 'antique' Meade 10" SCT (mounted on the CPC fork) for night use thus no need  to try to resurrect the Celestron to its intended application.

[SthBohemia]

Got out the glue and pasted it (more or less) back together. I will be saved from disappoinment that I cannot get an extremely clear view of the horsehead nebula due to the skies within Czech Republic being polluted, cloudy, foggy, misty and only semi dark for 5 hours per night. The damage was actually worse than I remembered..