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Old 12-01-2009, 07:12 PM
Wavytone
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Wavytone is offline
 
Join Date: Jul 2008
Location: Killara, Sydney
Posts: 4,147
Quote:
Originally Posted by koputai View Post
I beg to differ Wavy
I'd guess you're a lot younger than I am - my exit pupil is barely 6mm at best.

I have also done some tests to find out the effect on your pupil is arising from the image you see in your scope - while you may be able to achieve much more than 6 mm fully dark adapted, within seconds of putting your eye to the scope, if there are some nice bright "diamonds" in the field of view - open clusters in particularly - your pupil will shrink in seconds. A safer bet is a 5 mm pupil IMHO in most conditions.

Secondly, the actual field of view is determined by the diameter of the field stop of the eyepiece. Between 2 eyepieces with identical field stops - say a 30mm with a 65 degree apparent FoV vs. a 42mm with say a 55 degree apparent FoV, the higher magnification of the 30mm gives a darker background and should be used in preference to the 42mm because you will see more faint detail in the 30mm, with the same actual FoV across the sky.
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