Does your corrector really need cleaning? It would have to be pretty dirty to really need a clean. Otherwise learn to live with it
It won't affect your views. It doesn't have to be spotless. Too much care can be more harmful than anything. My 2c.
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Originally Posted by 04Stefan07
Just a few quick ones.
1) I have seen many different ways to clean the corrector plate on an SCT. Some use solution, some say not to, some say to use a microfibre cloth in a circle motion while others say to wipe outward.
How do you clean your plate?
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I'd clean outwards radially no concentric motion. Microfiber might be a little rough. Think of it as a big lens, not window glass. It is coated and it does have a profile cut in the glass. More importantly put the shims back exactly where they were and also keep the same orientation for the glass.
DO NOT TIGHTEN the retaining ring back. Just "touch" pressure. One member tightened his on a C14 when it was cold. When the glass expanded back at room temperature during the day it split in half. Correctors are usually paired with primaries and secondaries so all the elements are figured to work together. You cannot replace a broken corrector. Not with a Celestron anyway. Maybe Meade are more generic, I'm not sure. But I know that with Celestron usually the last bit getting figured is the smallest one: the secondary. And the optical path is tested for aberrations with the primary and corrector in place. So the corrector cannot be swapped or you'll need a new secondary as well.
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Originally Posted by 04Stefan07
2) Have read a lot about collimating one of these and it seems pretty straight forward however all guides don't mention the best time to collimate the OTA. Daytime or night time? I know you can buy artificial stars to collimate during the day but for the unfamiliar user looking through an SCT, how can you tell if the star or planet you are looking at requires collimation where poor seeing conditions can be the cause?
Cheers!
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You can use an artificial star no problem to collimate during the day. You'll need at least 20m or 40m line of sight on a grassy field to minimise seeing. It will get you ball park. A star test is best done at the zenith with the mirror rested in its cell. Out of collimation will show the star flaring sideways. If you want pick a double star then collimate until the separation is nice and clear and the two stars look nice and round.
When you use an artificial star because there is no drift you'll be able to go to very high magnification to the point you'll see the airy disc and the little dot in the middle with the first (maybe the fainter second) concentric ring. It will be obvious when you're collimated.