Thread: F-ratio myth
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Old 22-02-2018, 01:10 PM
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Camelopardalis (Dunk)
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Camelopardalis is offline
Join Date: Feb 2013
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Originally Posted by Peter Ward View Post
Well I've give you the Airy disc size.... is solely determined by F-ratio....but suspect the seeing will swamp any differences in practice.
That would be determined by the focal length... an f/4 at 800mm may not be "seeing limited" on a half decent night, whereas the seeing that night might not support good results from a f/8 at 1600mm... same aperture, but different results
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