4
Adjusting Binoculars:
Adjusting the Interpupillary Distance (IPD)
Since the distance between the eyes varies
among individuals, the two eyepieces of the
binoculars must be correctly aligned (adjusted).
This is called adjusting the interpupillary distance.
To adjust this distance, lift the binoculars up to
your eyes (using both hands) and look through
them at an object in the distance. Move the two
halves of the binoculars around the hinge until
you see one clear circle of image through both
eyes.
Adjusting Focus
Most people have a variance of vision from their
left to their right eye. To adjust the focusing
system, (1) Close your right eye and look through
the left side of the binoculars with your left eye at
the subject matter. Rotate the center focusing
wheel until the image appears in sharp focus; (2)
Close your left eye and look through the right
eyepiece (called the diopter). Rotate the right
eyepiece until the image appears in sharp focus.
(3) Now look through both eyepieces with both
eyes open. Since you’ve already adjusted the
right eyepiece, use only the center focusing
wheel to refocus on a new object at a different
distance.