Quote:
Originally Posted by multiweb
Yes but in this case we're talking about an 11" SCT with an F/2 primary. The secondary (F/5) is taken out. So it's not like you're correcting an F/10 primary on a newtonian.
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It doesn't matter.
For equivalent CCD or CMOS exposures, the number of photons collected is dependent on the diameter of the mirror (or lens). Unlike stopping down a camera lens, you are using the same diameter mirror in which case you won't be going any deeper using the optical system at f/2.
Note the principle doesn't apply to photographic emulsions.
Regards
Steven