Celestron 10x42 Nature DX Binoculars (Black) - Manual (Page 5)

ENGLISH I 3
The interpupillary distance, or the distance
between the pupils, varies from person to
person. The binocular must be correctly aligned
(adjusted) to the distance between your pupils
to achieve a single, clear image. To adjust this
distance, lift the binocular up to your eyes (using
both hands) and look through them at an object
in the distance. Move the two barrels (halves)
of the binocular closer together or further
apart until you see a single, clear image (Fig. 2).
Check that the interpupillary distance is set
correctly every time you use your binocular.
ADJUSTING THE INTERPUPILLARY DISTANCE (IPD)
Fig. 2