scope sight

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 intensifierA telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. Sights are equipped with a referencing pattern (reticle) mounted in a focally appropriate position in its optical system to provide an accurate point of aim. Telescopic sights are classified in terms of the optical magnification (power) and the objective lens diameter.

The first experiments directed to give shooters optical aiming aids go back to the early 17th century. For centuries, different optical aiming aids and primitive predecessors of telescopic sights were created that had practical or performance limitations. Most early telescopic sights were fixed-power and were in essence specially designed viewing telescopes. Telescopic sights with variable magnifications appeared later, and were varied by manually adjusting a zoom mechanism behind the erector lenses. Other types of scopes include prism sights and low-power variable optics.