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Old 24-03-2010, 05:19 PM
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mithrandir (Andrew)
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mithrandir is offline
Join Date: Jan 2009
Location: Glenhaven
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Originally Posted by multiweb View Post
Good for you Frank. You'll have fun with your new toy.
What's important is your image scale:

206.265/600mm * 4.4um ~ 1.5 [ED80] [Atik]
206.265/600mm * 6.4um ~ 2.2 [ED80] [Canon]
Now a QHY8 on the back of a C8 gives:

206.265/2032*7.8 ~= 0.8

Originally Posted by multiweb View Post
Just plug your RC FL in mm in the formula below and it will give you your image scale. Anything around 1-1.5asp is good. 2-3 good for widefields. Under 1 to 0.5 need AO or very good seeing.
So I guess that explains the fuzzies, even when the Bahtinov mask says focus is excellent. Would I have more luck with the 0.63 or 0.33 focal reducer installed:

206.265/(2032*0.63)*7.8 ~= 1.3

206.265/(2032*0.33)*7.8 ~= 2.4
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