The exit pupil is the size of the opening through which the light passes and is transferred to your own pupil. On average, your pupil varies in size from 2 to 7 mm. If the exit pupil is bigger than your pupil, it is easy to see an image. If the exit pupil is smaller, it becomes much more difficult to get a good image. To calculate the exit pupil value, divide the lens size by the magnification factor.
Exit pupil = size of the lens / magnification factor
Do you want to use binoculars at night? When purchasing your binoculars, keep in mind that your pupil opens up to a maximum of 5 to 7 mm in dark situations. For night vision equipment, it is important to know that the exit pupil is at least as big as the human pupil in low light. For example, a 7x50 binoculars would be suitable with an exit pupil of more than 7 mm, which is bigger than the human pupil.