etro-310x310.png"/> <-- retina iPhone pre iOS 7 -->

Exit pupil-Astronomy

Not sure what brand or model of binoculars is right for you? We're happy to help! Discuss and review your latest binocular purchase, share your experience and help others.

Exit pupil-Astronomy

Postby CDonoso. on Sat Feb 18, 2012 5:28 pm


I was wondering if a 3.1 exit pupil, ¿Is it enough for an astronomical binocular?



Re: Exit pupil-Astronomy

Postby Jne_K on Sun Feb 19, 2012 7:00 pm


Generally, the classical advice is to stay with at least a 4 mm exit pupil and 5 is better, but with today's high magnification astronomy binoculars, such as 30x80s, 22 x70s, 16x50 and so on, lot's of 3mm or so exit pupils binos being used. Probably more important to stay with a large objective in the neighborhood of 50 mm and up to get that 3 mm exit pupil, though, for the sake of resolution.

A 16x50 would be a fine choice for observing bright, small to mid-size open clusters, splitting double star and a great choice for observing the moon (when placed on a tripod). it would be at a disadvantage for dimmer objects such as faint nebulae and galaxies. For a more general purpose astronomy binocular, a 5mm exit pupil is better, yes, but a 16x50 with it's 3+ exit pupil is still useful.
Thanks for posting with us
Joanie K - Your personal optics expert


Phone: (800) 504-5897
Fax: (847) 919-3003
Site Admin
Posts: 7665
Joined: Wed Sep 24, 2003 3:09 pm