Are Celestron SCT correctors *really* matched to the primary?

[25585]

What is the Vixen VMC200L?

[Peter Drew]

It's a variant of the catadioptric (lenses and mirrors to form the prime image) class of optical design. It has a primary mirror and a sub aperture corrector between the primary and secondary mirrors. A bit like a Maksutov but without a full aperture corrector. The system is "open" like a Newtonian and has a secondary support spider.

[ethan]

When i took off the cover on

 my Celestron SCT 8" corrector plate I was shocked to see that it was just thrown in there the little nylon screws were not engaged at all it was just slopping around bouncing off the screws so i dont think they match nothing up in the chinese made ones anyway i heard the bigger ones were american hand made.

[johninderby]

The Chinese made ones are more consistant quality wise than the old American made ones. manufacturing processes  have improved a lot and are the reason for improved consistancy and matching up is not required now.. There are many good examples of the old American made ones  but also some poor examples.

Edited August 16, 2020 by johninderby

[Macavity]

Boy, this is a venerable thread! But a question that had intrigued me.
(I had heard of the "vacuum" thing!) Sending back your first 3 or 4
SCT's was a mark of discerning Astronomers? (Indulgent dealers)? 😛

Sometimes things need "mechanical work". One can worry too much?
I did hear that some wouldn't appreciate better than 1/4 wavelength.
That is not to negate your concern re. the above! 🙂

[billhinge]

There are  a multitude of threads on cloudy whatsits; quite a good one where some guy sent his back to Celestron and they stated in the work  to be done that they would be rematched.

However having taken mine off a couple of times there were no manufacturers marks or serial number on my C11 so I made my own. If you  think  about it the corrector is a thick piece of glass resting on a metal ridge held down with a plastic ring and some screws. Hardly a precision tuneable optical cell. Then there is the back, how do you   know that all the optical elements are aligned? You probably need the advanced hotech laser with the new v9 process to check that

There is an Italian company that sell replacement correctors, how would they match to your Celestron if they never saw it?

Another  thread some guy  said he tried the corrector in various rotations with star test in between and there was not much difference.

Personally I don't  think it makes a  huge difference, I don't think  a SCT is a ultra high precision scientific  instrument depending on micron level tolerances but it comes down to  belief really

[billhinge]

Spent the afternoon doing  some final dusting  and putting the corrector back

The tube was flocked with protostar several years ago, just picked up a bit of fluff (how did it get in there ??)

I'll dig out the Hotech 3 laser jobbie next week