What do the numbers on optics mean?
The first number(s) indicate the magnification. It may be a single number (if the unit has a fixed power) or a range (such as 3-9 or 6-24) will be shown if the magnification (power) is variable.The second number, usually separated by an “x”, is the objective lens diameter shown in millimeters. For example, a binocular with the designation 10×42 would magnify the image by a factor of ten and would have an objective lens diameter of 42 millimeters.
