A telescopic sight is a device used to give an accurate point of aim for a firearm. Other sighting systems are iron sights, red dot sights, and laser sights .

Telescopic sights are classified in terms of the optical magnification and the objective lens diameter, e.g. 10 x 50. This would denote 10 times magnification with a 50 mm objective lens. In general terms, larger objective lens diameters are better (collect more light and give a wider field of view), the magnification power should be chosen on the basis of the intended use. There are also Adjustable Objectives sights where the magnification can be changed by manually turning one part, the syntax is the following : minimal magnification - maximum magnification x objective lens, e. g. 3-9x40.

Telescopic sights have both advantages and disadvantages relative to iron sights. Standard doctrine with iron sights is to focus the eye on the front sight and align it with the resulting blur of the target. Telescopic sights allow the user to focus on both the crosshair and the target at the same time. This, combined with telescopic magnification, clarifies the target and makes the target stand out against the background.

Telescopic sights are expensive, and require additional, different training to align. Sight alignment with telescopic sights is a matter of making the field of vision circular. Simo Häyhä preferred to use iron sights rather than telescopic sights to present less of a target. Sunlight reflecting from lenses, and that the sniper must raise their head higher with telescopic sights might reveal the sniper’s position.

See also

• Red dot sights