Regarding the scope, first of all, we have to figure out the types of sights, which are divided into three types, telescopic sights, reflective sights, and collimating sights. Among them, the telescopic sight is generally used as a sniper sight in the military field because it can "magnify" things in the distance, which is also the focus of our talk today; The reflective sight, and the collimating sight, do not amplify, but can reduce the shooter's aiming time, so in the military aspect, more as a melee aid, especially after the emergence of better reflective sights, the collimating sight has almost withdrawn from the stage of history.