column of light coming out of the
eyepieces. A larger objective lens
provides a wider column and allows
more light to enter your eyes when
your pupils dilate at night.
The average youthful pupil
dilates only to about 7mm even in
total darkness. As we age, our eyes’
ability to dilate gradually dimin-ishes, so a 5.25mm exit pupil may
deliver all the light your eye can use,
even in dim-light conditions. Therefore, a 42mm objective is a good,
practical compromise between
brightness and weight.
In daylight, when your pupils
contract to about 3mm, most of the
light coming out of the binoculars
will fall outside the pupil and never
enter your eyes at all. Making the
exit pupil larger won’t make the
image look any brighter.
What and How We Tested
Focus mechanism. Your primary interaction with binoculars is
focusing. This should be an intuitive, transparent experience.
There should be little or no slack.
One achieves the best focus by turning past the sharpest point and then
back to it. Slack in the focus mechanism messes with this strategy.
Also, if you detect sloppiness while
turning the focus knob, it raises
doubts about the overall quality of