The telescopic sight has a magnifying function, which can clearly see and identify distant targets and is suitable for long-distance accurate shooting. Because it is often used for sniper purposes, it is usually called a sniper sight.
The optical system of telescopic sight is still Kepler telescopic system with image conversion system, as shown in the left picture. The basic structure consists of objective lens, mirror and eyepiece, plus a reticle. There are aiming marks on the cross line. You can aim at targets at different distances by moving the crosshair or using the crosshair at different positions. Some sights also have zoom function, aiming at short-range targets with low magnification and shooting at long-range targets with high magnification.
Crosshairs are the most common division of this kind of sight, but in the early sight, there was only this group of crosshairs. Later, the manufacturer added a reticle to measure the distance and angle. The principle is simple, and the distance is estimated by comparing the height (or width) of the reticle with the reference object.
The crosshair of the deer hunting mirror produced by Springfield Arsenal is based on the physique of an adult deer, and the height of different distances is marked on the crosshair, with a maximum range of 700 yards. This aiming division looks complicated, but it is simple to use. Without strict training, it can be used after simple explanation, so it is widely used. Many sights, even simple sights including disposable rocket launchers, adopt this division, but the marking methods are different.
The division of dense points seems simple, just mark small black dots on the cross. On the LeupoldM3 10 magnifying sight, there is a secret position between every two adjacent black spots. The close-range sight is not easy to use and needs strict training, but the measured value is quite accurate. It can help you learn to use the dense point measurement method, but it is only used for learning, because under actual combat conditions, snipers are not allowed to measure the target distance with a slide rule.