Quote:
Originally Posted by pkinchington
Hi Martin,
Excellent work getting the stars round what was the backfocus for your corrector?
Cheers Kanga
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Thanks
My 6” f6 newt was 55mm
My new 10” f5 Carbon fibre newt was 55mm ( I’m still building this scope but unguided 60 sec subs were excellent across the whole frame )
Haven’t tested my 8” f5 newt as it’s in my Dome on the South Coast NSW and I’ve been in Sydney for a few months , but probably 55mm too.
Prior to narrowing down the issue of Star shape in the off axis regions to the coma corrector, I did check and test for the following possible causes -
Polar alignment ( including image shift / rotation )
Primarily mirror pinched optics
Camera tilt
Guiding especially Dec backlash
Collimation
And so on ....
Cheers
Martin