Telescopic sight

A telescopic sight, commonly called a scope for short, is an optical sighting device based on a refracting telescope.[1] It is equipped with some form of a referencing pattern – known as a reticle – mounted in a focally appropriate position in its optical system to provide an accurate point of aim. Telescopic sights are used with all types of systems that require magnification in addition to reliable visual aiming, as opposed to non-magnifying iron sights, reflector (reflex) sights, holographic sights or laser sights, and are most commonly found on long-barrel firearms, particularly rifles, usually via a scope mount. The optical components may be combined with optoelectronics to form a digital night scope or a "smart scope".

View through a 4× telescopic sight
Leupold and Stevens Mark 6 scope with variable magnification X3-X18, mounted on an M24 SWS
German military sniper rifle with a mounted telescopic sight and dismounted NSV80 clip on optoelectronic image intensifier