Telescopic sight

A telescopic sight, commonly called a scope, is a device used to give an accurate point of aim for weapons such as firearms, airguns and crossbows. Other sighting systems are iron sights, red dot sights, and laser sights.

This article will concentrate on firearm scopes; the principles described are equally applicable to any device which needs aiming. For the sake of brevity, the term gun will be used to indicate any device aimed by a telescopic sight.