The C79 optical sight (SpecterOS3.4x) is a telescopic sight manufactured by Elcan. A variant, the M145 Machine Gun Optic is in use by the US military. It is 3.4×28, meaning 3.4x magnification, and a 28mm diameter objective lens. A tritium illuminated reticle provides for normal and low-light conditions sighting. It can be mounted to a variety of rifles and light machine guns using the Picatinny rail mounting system or the similar Diemaco rail system found on small arms produced by Diemaco/Colt Canada. Similar rifle sights are the Sight Unit Small Arms, Trilux (SUSAT) and the Advanced Combat Optical Gunsight (ACOG).
A C79 Optical Sight
A Canadian soldier with a C7A1 assault rifle equipped with a C79
Canadian soldiers training with C9A1 light machine guns equipped with a C79
C79 3.4×28 sight adjustment controls
A telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. 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. Similar devices are also found on other platforms such as artillery, tanks and even aircraft. The optical components may be combined with optoelectronics to add night vision or smart device features.
View through a 4× telescopic sight
Leupold and Stevens Mark 6 scope with variable magnification X3-X18, mounted on an M24 SWS
Telescopic sight (German made ZF Ajack 4×90 (4×38 in modern terminology) for the World War II pattern Swedish sniper rifle m/1941.
The Zielgerät ZG 1229 Vampir displayed by a British soldier (ca 1945)