The exit pupil is a bright circle that can be seen in the center of each eyepiece when you hold binoculars about 30cm (arm’s length) from your eyes with the objective lenses pointed toward a bright light. The diameter of the bright circle helps determine how much light will reach your eye. To determine the exit, divide the diameter of the objective lens by the magnification of the binocular. For example, a 10×32 binocular has an exit pupil of 3.2 millimeters. All binoculars with the same magnification and objective lens size have the same exit pupil diameter. Your pupils will adjust to the amount of light outside, whether low or bright light. A binocular that has a larger exit pupil can make your viewing field brighter, which is important to consider when using binoculars in dark situations or for astronomical observation.