Rifle scope reticles are markings in the sight of a rifle to allow people to accurately focus on a target. They are also known as crosshairs, a reference to the distinctive shape used for most styles of reticle, where two lines are crossed to turn the scope into a set of four quadrants with the intersection of the lines in the middle. Many people are familiar with rifle scope reticles as a result of their presence in pop culture, where they are often used in imagery for dramatic effect.
Various visual guides to assist with sighting targets have been present with firearms and other weapons for a long time. In the case of rifle scope reticles, the lines are built into the structure of the sight. They may be made with fine hair or wire, or etched into the glass. Most are set up in the second plane of the scope so that as the shooter zooms in to enlarge the target, the reticles retain their original size, rather than magnifying. If the reticles are located in the first plane, they will get bigger with magnification.
The simplest design is just two crossed lines. Sometimes, rifle scope reticles have a dot or circle at the center point to assist with aiming. Others may have thickened lines. Some include compensation for bullet drop; when a bullet is fired, it drops towards the ground as it moves, and thus shooting straight would cause someone to miss the target. Adjusting the sights of the gun compensates for this and allows people to shoot more precisely.
Rifle scope reticles can also include rangefinding markings, in a design known as mildot. These can be embedded in a variety of ways. There may be dots, ticks, or hatches to help people with rangefinding activity. Finally, rifle scope reticles can be illuminated for sighting in low light conditions. The potential drawback of illumination is contraction of the pupils, making it harder to see the surrounding environment.
Rifle scopes are provided with specification sheets discussing their reticles and other design features. For certain applications, the type of rifle scope reticles used can be important, while for others, it may not matter unless a shooter has a preference. In all cases, before using a scope, people need to focus the reticles by aiming the scope at a blank wall or similarly bland background and adjusting the focus ring until the lines appear crisp and sharp. The focus ring can be locked so people do not need to repeat this process.