what does diopter adjustment mean in binoculars
Most of today's binoculars will allow you to separately adjust the focus on one eye (usually the right eye) with a diopter. This is done to compensate for differences between your eyes so you see the clearest image possible through your binoculars. To make the diopter adjustment, pick a distinctive object to focus on that is beyond the close focus distance of the binocular, but not too far out in the distance.