The age of the shooter will affect the expansion of the eye. Older people will experience lesser expansion than younger people. When choosing your range, it is important to have a pupil distance. Basically, an exit pupil can be determined by holding the length of your arm. When this is the time, the small aperture that appears in the eyepiece is the exit pupil. When considering the relaxation of the eye, the export of the pupil is very important, because the greater the export pupil, the less important the importance of the field of vision.
When talking about the rifle distance from the rifle sight, the distance of the eye is the distance your eyes can be away from the eyes of the eye, and still provide a complete and clear picture of your goals. At present, four inches are the biggest eye within any standard rifle. If you are using the right rifle, away from your face 4 inches away, your rifle may be back. At the time of purchase, you should always pay attention to the distance between the pupil and the size of the exit pupil.