What do the numbers in a bainocular name mean?
The numbers on a binocular describe its configuration. Let’s take 8×42 binoculars as an example. The first number (8) refers to the magnification, or, how many times closer an object will appear when looking through the binocular compared to looking at the same object with the naked eye. The second number (42) indicates the diameter of the objective lens (the light-gathering lens) in millimeters.
Magnification:
Consider this general rule about optics: low magnification provides a wide field of view and is easy to hold steady. So although a magnification of 10, 12 or higher is available, 6, 7, and 8-power binoculars are easier to use and in many cases more practical.