How to strip and clean the optics of a SCT (Schmidt-Cassegrain Telescope)

This video gives step-by-step instructions on how to safely remove the Schmidt-plate (corrector) from a SCT. It then continuous to show the proper method of cleaning the Schmidt-plate as well as the primary mirror, in-situ. After assembly, the collimation was also done. Although SCTs are quite similar, the specific telescopes shown here are a 16-inch Meade LX200 and a 14-inch Celestron.


Matthew Kerner says:

Hi, I have a Schmidt cassegrain telescope that has collected mold on the corrector plate and the primary mirror over time. Would I be able to clean the mold with this method, and how has the mold effected the mirror? It has been sitting in a basement for over 5 years. Thank you.

Tim Chemaly says:

Willie why does it matter how the corrector plate was originally rotated? Isn’t the surface of the corrector the same regardless of rotation?

ANONIM says:

very cool! But I have a questions what is better look? celestron 1400-inch? or meade 16-inch? what a better quality optics?

DelBoy 1967 says:

Thank you, this video gave me the confidence to clean my sons recently purchased CPC 800, it’s secondhand and the inside seemed too much dust for my liking. Went through a lot of cotton balls trying to dry up the water :), used a small amount of dish-washing detergent.

FedericoCPP says:

Excellent video! Thanks for showing each step! Even removing the corrector plates.

thomas CANADIAN says:

how many granular in the water

Oleg Bouevitch says:

Nice video and voiceover

Khalil says:

Hello Willie,,
I have NexStar 6SE
But the corrector plate is broken.

How i can get a new one ??

Jan Kotze says:

Willie, my seun het Celestron Astromaster 130 EQ en n Celestron vergroot teleskoop, die laas genoemde het nie probleme nie maar die 130 EQ het uit fokus gegaan, dis wat ons vermoed, is daar n manier om dit reg te stel of moet hy iewers heen gestuur word, dis die lig versameling teleskoop. Ons hoor graag van jou, dankie vir video

Dan Morris says:

After just a few years of use, I have the need to address cleaning, and this hugely helpful. I am very reluctant to “pop the seal”, and wondering what preventative steps we can take to keep it clean, once we finish. (Building a fine observatory helps!. Very impressive facility, I might add.). Clear skies, Willie!

Robert Jensen says:

As a professional photographer I’d never put any liquid on a lens directly, nor in such amounts as to form drops that could get in between the lens element/glass filter and the ring holding it in place. I would think if you had a cemented double lens that any liquid could get in between the lenses and play havoc with the cement. With a SCT you run the risk of water getting inside the tube and causing damage. (Ever see mold growing inside a photographic lens?)

In photography you’d first blow any loose particles off with compressed air (use caution) or clean blower brush positioning the front of the lens horizontally or facing downwards so that any dirt falls away from the lens and not re-deposited on it. FOr any stubborn dirt I’d lightly use a dry tissue or clean microfiber cloth then follow up with a DAMP, lint free, tissue or cloth and lightly wipe the glass in a circular motion with multiple tissues if needed until clean.

If you had no other option than to use dish soap (which is actually a detergent) and distilled water you only need a drop or two of the detergent. This is how professional window cleaners work. You only need enough detergent to break surface tension.

Forgetting that, before you do anything I’d first read the scope’s manual for cleaning instructions or contact the manufacturer repair department for instructions.

Here is a safer way to clean your corrector.

I disagree with his use of the word ‘firmly’ when wiping with the Pec Pads (Pec Pads are something I use myself). Lightly wipe so you don’t grind and dirt into the glass causing scratched or damaging fragile coatings.

Khalil says:

Hello Willie,,
I have NexStar 6SE
But the corrector plate is broken.
How i can get a new one ??

J0llyR0ger says:

Oh the Horror!! Your roll off observatory is AWESOME however!

kirostar12 says:

Nice video. I was cleaned successfully with detergent and clean water. But I removed the prime mirror first. Your way is little more difficult but you don’t need to remove the mirror itself. So if that’s work you can keep doing that.

FlyBuy777 says:

Thanks for taking the time to share this video. Very informative. If you are just cleaning outside of corrector and not removing it would it be best to point tube down to prevent water from running down tube. I just need to clean the outside of mine for now.

Dennys Turcotte says:

Thanks for the video Willie.

Mike Lubiarz says:

Great video however, in the beginning of the video you show a view of the “cleaned” C14 and the corrector plate is badly scratched. A little dis-concerning…….

T. Scott Nalley says:

Thank you for the great video. I have a question about this. What can I do to find the correct position of the corrector plate if I have removed it before I knew it must be indexed a certain way? My problem is that I have taken it apart once and didn’t mark it for reassembly. Thank you, Scott

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