Free Binocular Exit Pupil Calculator
Calculate the exit pupil of binoculars or a telescope eyepiece: exit_pupil = aperture / magnification.
mm
×
Exit Pupil
5.00 mm
Exit Pupil vs Objective Aperture
Exit Pupil
Exit Pupil = Aperture / Magnification
The exit pupil is the diameter of the light beam leaving the eyepiece. For the brightest possible image, the exit pupil should match your eye's pupil (5-7 mm in darkness).
Example Calculation
10×50 binoculars (50 mm aperture, 10×).
- 01Exit pupil = 50 / 10 = 5.0 mm
- 02Excellent for astronomical use with a dark-adapted eye.