Ocular dominance.
Normally, one eye is dominant, just as one person is left-handed or right-handed. In general, for the right-handed persons, the right eye is dominant.
Ocular dominance is an important factor in some sports such as shooting, because competitors will use the dominant eye to aim. You can find out which eye is dominant in your case if you look with both eyes simultaneously at an object about five meters away.
If you close one eye at a time, you will notice that one eye does not “target” well. The eye that aims better is the dominant eye for distance. Ocular dominance is also relevant for the monocular vision, a way to correct vision problems due to age. Often it is much easier to use the dominant eye for distance and the non-dominant eye for reading. The eye you prefer to use when looking through the camera lens is the dominant eye for distance.
