"George Kinney" wrote in message ...

The more light that reaches your retina the better. Unfortunately, an exit
pupil that exceeds your eyes pupil doesn't do that, it actually will cause
contrast and brightness to suffer.

No, I don't think so. I tried some experiments with a friend's 8x56
binoculars, using circular masks of various sizes to modify them
down to 8x52, 8x48, 8x44, and 8x40. As far as I could tell, the
view through the binoculars with the 44mm mask was *exactly* the
same as through the unmasked binoculars. That agrees with a
measurement of 5.5mm for my pupils derived from other methods.

In other words, for any given magnification, the only drawbacks
for having an exit pupil wider than your eye's pupil is that
the binoculars are unnecessarily heavy and bulky, and possibly
unnecessarily expensive as well. A significant advantage is
that they are more forgiving about eye placement; when the
exit pupil matches your own pupils precisely, you lose light
unless your eyes are *precisely* behind the centers of the
eyepieces, which can be hard to achieve.

A propos of field of view, the true FOV of most 10x50 binoculars
is 5 degrees, but there are also several highly respected
wide-angle models with FOVs of 6.5 degrees or wider, nearly
as wide as standard 7X binoculars.

Having said all that, I must admit that I love my 7x35 binoculars,
and use them fairly frequently in preference to my 10x50. But
they certainly can't see such faint objects -- not even close!

- Tony Flanders