Telescopic sight in the context of Shooting games

Leica Camera AG (/ˈlaɪkə/) is a German company that manufactures cameras, optical lenses, photographic lenses, binoculars, and rifle scopes. The company was founded by Ernst Leitz in 1869 (Ernst Leitz Wetzlar), in Wetzlar, Germany. The name Leica is derived from the first three letters of the founder's surname (Leitz) and the first two of the word camera: lei-ca (LEItz CAmera).

In 1986, the Leitz company changed its name to Leica and moved its factory from Wetzlar to the nearby town of Solms.

An optical axis is an imaginary line that passes through the geometrical center of an optical system such as a camera lens, microscope or telescopic sight. Lens elements often have rotational symmetry about the axis.

The optical axis defines the path along which light propagates through the system, up to first approximation. For a system composed of simple lenses and mirrors, the axis passes through the center of curvature of each surface, and coincides with the axis of rotational symmetry. The optical axis is often coincident with the system's mechanical axis, but not always, as in the case of off-axis optical systems.

A sight or sighting device is any device used to assist in precise visual alignment (i.e. aiming) of weapons, surveying instruments, aircraft equipment, optical illumination equipment or larger optical instruments with the intended target. Sights can be a simple set or system of physical markers that serve as visual references for directly aligning the user's line of sight with the target (such as iron sights on firearms), or optical instruments that provide an optically enhanced—often magnified—target image aligned in the same focus with an aiming point (e.g. telescopic, reflector and holographic sights). There are also sights that actively project an illuminated point of aim (a.k.a. "hot spot") onto the target itself so it can be observed by anyone with a direct view, such as laser sights and infrared illuminators on some night vision devices, as well as augmented or even virtual reality-enabled digital cameras ("smart scopes") with software algorithms that produce digitally enhanced target images.

A sniper rifle is a high-precision, long-range rifle. Requirements include high accuracy, reliability, mobility, concealment, and optics, for anti-personnel, anti-materiel and surveillance uses by military snipers. The modern sniper rifle is a portable shoulder-fired rifle with either a bolt action or semi-automatic action, fitted with a telescopic sight for extreme accuracy and chambered for a high-ballistic performance centerfire cartridge.

Shooter video games, or shooters, are a subgenre of action video games where the focus is on the defeat of the character's enemies using ranged weapons given to the player. Usually these weapons are firearms or some other long-range weapons, and can be used in combination with other tools such as grenades for indirect offense, armor for additional defense, or accessories such as telescopic sights to modify the behavior of the weapons. A common resource found in many shooter games is ammunition, armor or health, or upgrades which augment the player character's weapons.

Shooter games test the player's spatial awareness, reflexes, and speed in both isolated single player or networked multiplayer environments. Shooter games encompass many subgenres that have the commonality of focusing on the actions of the avatar engaging in combat with a weapon against both code-driven NPC enemies or other avatars controlled by other players.

A monocular is a compact refracting telescope used to magnify images of distant objects, typically using an optical prism to ensure an erect image, instead of using relay lenses like most telescopic sights. The volume and weight of a monocular are typically less than half of a pair of binoculars with similar optical properties, making it more portable and also less expensive. This is because binoculars are essentially a pair of monoculars packed together — one for each eye. As a result, monoculars only produce two-dimensional images, while binoculars can use two parallaxed images (each for one eye) to produce binocular vision, which allows stereopsis and depth perception.

Monoculars are ideally suited to those applications where three-dimensional perception is not needed, or where compactness and low weight are important (e.g. hiking). Monoculars are also sometimes preferred where difficulties occur using both eyes through binoculars due to significant eyesight variation (e.g. strabismus, anisometropia or astigmatism) or unilateral visual impairment (due to amblyopia, cataract or corneal ulceration).

A night-vision device (NVD), also known as a night optical/observation device (NOD) or night-vision goggle (NVG), is an optoelectronic device that allows visualization of images in low levels of light, improving the user's night vision.

The device enhances ambient visible light and converts near-infrared light into visible light which can then be seen by humans; this is known as I (image intensification). By comparison, viewing of infrared thermal radiation is referred to as thermal imaging and operates in a different section of the infrared spectrum.

A sniper is a military or paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with telescopic sights. Modern snipers use high-precision rifles and high-magnification optics. They often also serve as scouts or observers feeding tactical information back to their units or command headquarters.

In addition to long-range and high-grade marksmanship, military snipers are trained in a variety of special operation techniques: detection, stalking, target range estimation methods, camouflage, tracking, bushcraft, field craft, infiltration, special reconnaissance and observation, surveillance and target acquisition. Snipers need to have complete control of their bodies and senses in order to be effective. They also need to have the skill set to use data from their scope and monitors to adjust their aim to hit targets that are extremely far away. In training, snipers are given charts to ensure they can make last-minute calculations in the field.

A marksman is a person who is skilled in precision shooting. In modern military usage this typically refers to the use of projectile weapons such as an accurized scoped long gun such as designated marksman rifle (or a sniper rifle) to shoot at high-value targets at longer-than-usual ranges.

The proficiency in precision shooting is known as a shooter's marksmanship, which can be used to describe both gunnery and archery.

Iron sights are a system of physical alignment markers used as a sighting device to assist the accurate aiming of ranged weapons such as firearms, airguns, crossbows, and bows, or less commonly as a primitive finder sight for optical telescopes. Iron sights, which are typically made of metal, are the earliest and simplest type of sighting device. Since iron sights neither magnify nor illuminate the target, they rely completely on the viewer's naked eye and the available light by which the target is visible. In this respect, iron sights are distinctly different from optical sight designs that employ optical manipulation or active illumination, such as telescopic sights, reflector (reflex) sights, holographic sights, and laser sights.

Iron sights are typically composed of two components mounted perpendicularly above the weapon's bore axis: a 'rear sight' nearer (or 'proximal') to the shooter's eye, and a 'front sight' farther forward (or 'distal') near the muzzle. During aiming, the shooter aligns their line of sight past a gap at the center of the rear sight and towards the top edge of the front sight. When the shooter's line of sight, the iron sights, and target are all aligned, a 'line of aim' that points straight at the target has been created.

A laser sight is a device attached or integral to a firearm to aid target acquisition. Unlike optical and iron sights where the user looks through the device to aim at the target, laser sights project a beam onto the target, providing a visual reference point.

Although lasers in the visible part of the spectrum are most common, invisible infrared (IR) lasers may be used in conjunction with a night vision device. As they are offset from the barrel, laser sights need to be zeroed in, much like a conventional sight, so that the beam intercepts the point of impact at a chosen distance. Devices may include one or both types of laser, with some models also incorporating a rangefinder, flashlight, or IR illuminator. Laser sights may be attached to the existing sighting mechanism, the trigger guard, via a rail system, or can be integrated into replacement components such as the guide rod or grip plates. Some variants are also incorporated into other attachments such as foregrips.

A varmint rifle or varminter is a type of small-caliber, precision-oriented long gun (firearm or high-powered airgun) primarily used for varmint hunting and pest control. Such rifles are typically characterized by sniper rifle-like designs such as heavy free-floating barrel, enhanced bedding, ergonomic gunstock, the use of bipod/beanbag and high-power telescopic sight, and the choice of high-muzzle velocity, high-ballistic coefficient munitions, which are all accurizing features needed for improving repeated shooting, often over long distances.

Both varmint hunting (which eliminates harassing outdoor nuisance animals collectively called varmints) and pest control (which removes infestations of destructive, often indoor pests) typically target animals that are difficult to eradicate by conventional hunting techniques due to their sheer numbers, burrowing or escape behaviors, camouflaging and defilading by the surroundings, or long alert distances that prevent easy approach or detection. These target animals typically come in three groups:

The M40 rifle is a bolt-action sniper rifle used by the United States Marine Corps. It has had four variants: the M40, M40A1, M40A3, and M40A5. The M40 was introduced in 1966. The changeover to the A1 model was completed in the 1970s, the A3 in the 2000s, and the A5 in 2009.

Each M40 is built from a Remington Model 700 bolt-action rifle, and is modified by USMC armorers at Marine Corps Base Quantico, using components from a number of suppliers. New M40A5s are being built, and A1s are upgraded to A3s and A5s as they rotate into the armory for service and repair. The rifles have had many sub-variations in telescopic sights, and smaller user modifications. The M40A5 incorporates a detachable magazine and a threaded barrel to allow for the use of a sound suppressor or another muzzle device.

The M24 Sniper Weapon System (SWS) or M24 is the military and police version of the Remington Model 700 rifle, M24 being the model name assigned by the United States Army after adoption as their standard sniper rifle in 1988. The M24 is referred to as a "weapon system" because it consists of not only a rifle, but also a detachable telescopic sight and other accessories.

The M24 SWS has the "long action" bolt version of the Remington 700 receiver but is chambered for the 7.62×51mm NATO "short action" cartridge that has an overall length of 2.750 inches (69.85 mm). The "long action" allows the rifle to be re-configured for dimensionally larger cartridges up to 3.340 inches (84.84 mm) in overall length.

The Accuracy International Arctic Warfare rifle is a bolt-action sniper rifle designed and manufactured by the British company Accuracy International. It has proved popular as a civilian, police, and military rifle since its introduction in the 1980s. The rifles have features that improve performance in extremely cold conditions (which gave the rifle its name) without impairing operation in less extreme conditions.

Arctic Warfare rifles are generally fitted with a Schmidt & Bender Police & Military II (PM II) telescopic sight with fixed or variable magnification. Variable telescopic sights can be used if the operator wants more flexibility to shoot at varying ranges, or when a wide field of view is required. Accuracy International actively promotes fitting the German-made Schmidt & Bender PM II product line as sighting components on their rifles, which is rare for a rifle manufacturer. The German and Russian forces preferred a telescopic sight made by Zeiss over Accuracy International's recommendation.