Bino for the night sky?

Ultralightbackpacker wrote in
:

7x50 is too large an exit pupil (over 7mm), unless you are very young
or a mutant. 8x42 is a much more workable size.

My personal favorites are the Canon IS 15x50s, which would normally be
too powerful to hand hold, but image stabilization makes them useable
without a tripod. They slightly more expensive than your target price
at $700+, although Canon frequently offers $100 rebates.

Is the 7mm just a waste or does it actually cause problems. For
example I know that when eye relief is very long, this causes some
issues.

I am 32 so I don't fit theyoung crowd, and am wearing prescription
glasses.

I don't think it really causes problems... it's just that the light in
excess of your pupil diameter is never even entering your pupil, so you
paid for something you aren't getting.

If you have astigmatism, and need to wear glasses to use your binoculars
then eye relief needs to be long. Otherwise the diopter adjustment on the
binoculars should be able to compensate for your eyes.

I hope someone else who knows a lot more about this than me, will
elaborate.