We can supposedly quantify image sharpness and brightness by looking at optics charts in both daylight and dim light, but such tests are themselves slightly subjective — and, I’ve found, not any better than letting various people look through the same glass and make their own judgments.  So while I periodically perform lab tests on various glasses, more often I have a few friends over to look through a bunch of binoculars.  This also tends to reveal mechanical and ergonomic factors that may not appeal to all hunters.

Just such a test took place a couple of weeks ago, when two friends stopped over for an extensive binocular look-through.  Both had come into a little extra money, thanks to a highway project that had eaten some of the land surrounding their country homes, so they decided to spring both for a caribou hunt and new binoculars.  

Neither wanted a compact binocular, a decision I totally agreed with.  While tiny binoculars can be very handy in hunting, especially with a bow, they just don’t pack it in dimmer light — or when glassing seriously for long periods, especially in windy country.  This is typical of caribou hunting.  So my wife and dragged out every binocular in the house with at least a 4mm exit pupil.  This is important when choosing an all-around hunting binocular.  

For those not familiar with the term, the exit pupil is that tiny circle of light seen when you hold up a binocular (or telescope) at arm’s length.  The circle is the actual amount of light that leaves the binocular to enter your eye.  The bigger its diameter, the better you’ll see in dim light, up to the maximum diameter of the human pupil itself, generally recognized as 4mm to 7mm, depending on our age and available light.