Sight (device)
Encyclopedia
A sight is a device used to assist aligning or aim weapons, surveying instruments, or other items by eye. Sights can be a simple set or system of markers that have to be aligned together as well as aligned with the target (referred to as an iron sight
Iron sight
Iron sights are a system of shaped alignment markers used as a sighting device to assist in the aiming of a device such as a firearm, crossbow, or telescope, and exclude the use of optics as in telescopic sights or reflector sights...

s on firearms). They can also be optical devices
Optical instrument
An optical instrument either processes light waves to enhance an image for viewing, or analyzes light waves to determine one of a number of characteristic properties.-Image enhancement:...

 that allow the user to see the image of an aligned aiming point in the same focus as the target. These include telescopic sight
Telescopic sight
A telescopic sight, commonly called a scope, is a sighting device that is based on an optical refracting telescope. They are equipped with some form of graphic image pattern mounted in an optically appropriate position in their optical system to give an accurate aiming point...

s and reflector (or "reflex") sight
Reflector sight
A reflector or reflex sight is a generally non-magnifying optical device that allows the user to look through a partially reflecting glass element and see an illuminated projection of an aiming point or some other image superimposed on the field of view...

s. There are also sights that project an aiming point onto the target itself, such as laser sights.

Simple sights

At its simplest, a sight is typically composed of two components, front and rear aiming pieces that have to be lined up. Sights such as this can be found on many types of devices including weapons, surveying
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

 and measuring instruments, and navigational tools.

On weapons, these sights are usually formed by rugged metal parts, giving these sights the name "iron sights
Iron sights
Iron sights are a system of shaped alignment markers used as a sighting device to assist in the aiming of a device such as a firearm, crossbow, or telescope, and exclude the use of optics as in telescopic sights or reflector sights...

", a term relative to other weapon sights in that they are not optical or computing sights. On many types of weapons they are built-in and may be fixed, adjustable, or marked for elevation
Elevation (ballistics)
In ballistics, the elevation is the angle between the horizontal plane and the direction of the barrel of a gun, mortar or heavy artillery. Originally, elevation was a linear measure of how high the gunners had to physically lift the muzzle of a gun up from the gun carriage to hit targets at a...

, windage
Windage
Windage is a force created on an object by friction when there is relative movement between air and the object.There are two causes of windage:# the object is moving and being slowed by resistance from the air...

, target speed, etc. They also are classified in forms of notch (open sight) or aperture (closed sight). These types of sights can take considerable experience and skill in the user who has to hold a proper eye position and simultaneously focus on the rear sight, the front sight, a target at different distances, and align all three planes of focus.

Optical sights

Optical sights use optics
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...

 that give the user an image of an aligned aiming point or patern (also called a reticle) superimposed at the same focus as the target.

Telescopic sights

A telescopic sight
Telescopic sight
A telescopic sight, commonly called a scope, is a sighting device that is based on an optical refracting telescope. They are equipped with some form of graphic image pattern mounted in an optically appropriate position in their optical system to give an accurate aiming point...

 is an optical telescope
Optical telescope
An optical telescope is a telescope which is used to gather and focus light mainly from the visible part of the electromagnetic spectrum for directly viewing a magnified image for making a photograph, or collecting data through electronic image sensors....

 equipped with some form of graphic image pattern reticle mounted in an optically appropriate position in the optical system to give an accurate aiming point. Telescopic sights are used on a wide range of devices including gun
Gun
A gun is a muzzle or breech-loaded projectile-firing weapon. There are various definitions depending on the nation and branch of service. A "gun" may be distinguished from other firearms in being a crew-served weapon such as a howitzer or mortar, as opposed to a small arm like a rifle or pistol,...

s, Surveying
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

 equipment, and even as sights on larger telescopes (called a finderscope
Finderscope
A Finderscope is a small auxiliary telescope mounted atop the main astronomical telescope and pointed in the same direction. The finderscope usually has a much smaller magnification than the main telescope can provide and therefore can see more of the sky. This helps in locating the desired...

).

Reflector sights

Another type of optical sight is the reflector (or "reflex") sight
Reflector sight
A reflector or reflex sight is a generally non-magnifying optical device that allows the user to look through a partially reflecting glass element and see an illuminated projection of an aiming point or some other image superimposed on the field of view...

, a generally non-magnifying
Magnification
Magnification is the process of enlarging something only in appearance, not in physical size. This enlargement is quantified by a calculated number also called "magnification"...

 optical device that allows the user to look through a glass element and see a reflection of an illuminated aiming point or some other image superimposed on the field of view
Field of view
The field of view is the extent of the observable world that is seen at any given moment....

. These sights have been around for over 100 years and been used on all types of weapons and devices.

Reflector sights were first used as a weapon sight in German aircraft towards the end of World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. Over the years they became more sophisticated, adding lead computing gyroscopes and electronics (the World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 Gyro gunsight
Gyro gunsight
A gyro gunsight is a modification of the non-magnifying reflector sight in which target lead and bullet drop are allowed for automatically, the sight incorporating a gyroscopic mechanism that computes the necessary deflections required to ensure a hit on the target...

) radar range finding and other flight information in the 1950s and 60s, eventually becoming the modern head-up display
Head-Up Display
A head-up display or heads-up display is any transparent display that presents data without requiring users to look away from their usual viewpoints...

.

List of sights

There are many types of sighting devices. They can be fixed, mechanical, optical, computational
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

, or a mixture of all of these attributes.
  • Bombsight
    Bombsight
    A bombsight is a device used by bomber aircraft to accurately drop bombs. In order to do this, the bombsight has to estimate the path the bomb will take after release from the aircraft. The two primary forces during its fall are gravity and air drag, which makes the path of the bomb through the air...

  • Collimator sight
    Collimator sight
    A collimator sight is a type of optical sight that allows the user looking into it to see an illuminated aiming point aligned with the device the sight is attached to regardless of eye position...

  • Diopter sight
    Diopter sight
    The diopter is an aperture sight component used to assist the aiming of a guns/devices, usually those intended to launch projectiles, such as firearms, airguns, and crossbows...

  • Globe sight
    Globe sight
    A globe sight is a front sight component used to assist the aiming of a gun/device, usually those intended to launch projectiles, such as firearms, airguns, and crossbows...

  • Head-up display
    Head-Up Display
    A head-up display or heads-up display is any transparent display that presents data without requiring users to look away from their usual viewpoints...

  • Holographic weapon sight
    Holographic weapon sight
    A holographic weapon sight or holographic diffraction sight is a non-magnifying gun sight that allows the user to look through a glass optical window and see a reticle image superimposed at a distance on the field of view...

  • Iron sight
    Iron sight
    Iron sights are a system of shaped alignment markers used as a sighting device to assist in the aiming of a device such as a firearm, crossbow, or telescope, and exclude the use of optics as in telescopic sights or reflector sights...

  • Laser sight
  • Reflector sight
    Reflector sight
    A reflector or reflex sight is a generally non-magnifying optical device that allows the user to look through a partially reflecting glass element and see an illuminated projection of an aiming point or some other image superimposed on the field of view...

    • Gyro gunsight
      Gyro gunsight
      A gyro gunsight is a modification of the non-magnifying reflector sight in which target lead and bullet drop are allowed for automatically, the sight incorporating a gyroscopic mechanism that computes the necessary deflections required to ensure a hit on the target...

    • Red dot sight
      Red dot sight
      A red dot sight is a common classification for a type of non-magnifying reflector sight for firearms that gives the user an aimpoint in the form of an illuminated red dot...

  • Thermal Weapon Sight
    Thermal Weapon Sight
    A Thermographic weapon sight or Thermal Weapon Sight is a device combining a compact thermographic camera and an aiming reticle. They can be mounted on a variety of small arms as well as some heavier weapons....

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