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111-584: AN/PVS-4 ( Night Vision Sight, Individual Served Weapon, AN/PVS-4 ) is the U.S. military designation for a specification of the first second generation passive Night vision device . The AN/PVS-4 first saw widespread use during the Gulf War and later some deployment in the Iraq War and has since been replaced by modern third-generation weapon sights. Although passive night vision technology capable of allowing vision under ambient starlight conditions has existed since

222-511: A 25mm Gen3 tube. As these tubes were proximity focussed, it was necessary to add a Fiber-Optic inverter to the tube to both extend the optical length of the device and the Gen3 photocathode was also mounted in some cases on a Fiber Optic plate rather than the usual Gen3 glass plate to match the focal point of the AN/PVS-4 optics. These tubes provided significant performance increase in gain but very little in

333-450: A combination of lens design and post-processing: Wavefront coding is a method by which controlled aberrations are added to the optical system so that the focus and depth of field can be improved later in the process. The lens design can be changed even more: in colour apodization the lens is modified such that each colour channel has a different lens aperture. For example, the red channel may be f /2.4 , green may be f /2.4 , whilst

444-603: A detail at distance x d from the subject can be expressed as a function of the subject magnification m s , focal length f , f-number N , or alternatively the aperture d , according to b = f m s N x d s ± x d = d m s x d D . {\displaystyle b={\frac {fm_{\mathrm {s} }}{N}}{\frac {x_{\mathrm {d} }}{s\pm x_{\mathrm {d} }}}=dm_{\mathrm {s} }{\frac {x_{\mathrm {d} }}{D}}.} The minus sign applies to

555-401: A different field of view. If the focal length is altered to maintain the field of view, while holding the f-number constant , the change in focal length will counter the decrease of DOF from the smaller sensor and increase the depth of field (also by the crop factor). However, if the focal length is altered to maintain the field of view, while holding the aperture diameter constant ,

666-455: A given maximum acceptable circle of confusion c , focal length f , f-number N , and distance to subject u . As distance or the size of the acceptable circle of confusion increases, the depth of field increases; however, increasing the size of the aperture (i.e., reducing f-number ) or increasing the focal length reduces the depth of field. Depth of field changes linearly with f-number and circle of confusion, but changes in proportion to

777-448: A greater (or less, if so desired) apparent depth of field than any of the individual source images. Similarly, in order to reconstruct the 3-dimensional shape of an object, a depth map can be generated from multiple photographs with different depths of field. Xiong and Shafer concluded, in part, "...   the improvements on precisions of focus ranging and defocus ranging can lead to efficient shape recovery methods." Another approach

888-459: A lens focused at an object whose distance from the lens is at the hyperfocal distance H will hold a depth of field from H /2 to infinity, if the lens is focused to H /2 , the depth of field will be from H /3 to H ; if the lens is then focused to H /3 , the depth of field will be from H /4 to H /2 , etc. Thomas Sutton and George Dawson first wrote about hyperfocal distance (or "focal range") in 1867. Louis Derr in 1906 may have been

999-458: A lens; at that distance, a point object will produce a small spot image. Otherwise, a point object will produce a larger or blur spot image that is typically and approximately a circle. When this circular spot is sufficiently small, it is visually indistinguishable from a point, and appears to be in focus. The diameter of the largest circle that is indistinguishable from a point is known as the acceptable circle of confusion , or informally, simply as

1110-522: A replacement for the Vietnam War era AN/PVS-2 Starlight Scope. In 1976, the first production contract was awarded for 47,074 units, and first deployed in 1978. 16,927 more units were produced between 1985 and 1989 and 24,046 more units produced between 1990 and 1992. By 2002, more than 150,000 units had been produced within the United States alone. Although production has ceased, as recently as 2008

1221-536: A scene, so the focus and depth of field can be altered after the photo is taken. Diffraction causes images to lose sharpness at high f-numbers (i.e., narrow aperture stop opening sizes), and hence limits the potential depth of field. (This effect is not considered in the above formula giving approximate DOF values.) In general photography this is rarely an issue; because large f-numbers typically require long exposure times to acquire acceptable image brightness, motion blur may cause greater loss of sharpness than

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1332-428: A single aperture setting for interiors (e.g., scenes inside a building) and another for exteriors (e.g., scenes in an area outside a building), and adjust exposure through the use of camera filters or light levels. Aperture settings are adjusted more frequently in still photography, where variations in depth of field are used to produce a variety of special effects. Precise focus is only possible at an exact distance from

1443-658: A single organization. The mission of Army Aviation is to find, fix and destroy any enemy through fire and maneuver and to provide combat support and combat service support in coordinated operations as an integral member of the combined arms team. Major aircraft include the AH-64 Apache , which serves as the Army's attack helicopter, the UH-60 Black Hawk , and the CH-47 Chinook for troop and cargo transport. Army Aviation also flies

1554-453: A special operations force, Army Rangers are generally better equipped than standard infantry, utilizing the FN SCAR rifle. Army Special Forces , commonly known as Green Berets after their iconic headgear, are among the most elite soldiers in the Army. Special Forces conduct: Army Special Forces are trained in military free-fall parachuting and combat diver skillsets. They are considered

1665-483: A thin light plane across the subject that is mounted on a moving stage perpendicular to the light plane. This ensures the entire subject remains in sharp focus from the nearest to the farthest details, providing comprehensive depth of field in a single image. Initially developed in the 1960s and further refined in the 1980s and 1990s, LSP was particularly valuable in scientific and biomedical photography before digital focus stacking became prevalent. Other technologies use

1776-450: Is a distance from a lens beyond which all objects can be brought into an "acceptable" focus . As the hyperfocal distance is the focus distance giving the maximum depth of field, it is the most desirable distance to set the focus of a fixed-focus camera . The hyperfocal distance is entirely dependent upon what level of sharpness is considered to be acceptable. The hyperfocal distance has a property called "consecutive depths of field", where

1887-603: Is a surveillance device designed to make use of the Civilian version of the MX9644 tube, the F4845. It is thought that the F4845 were tubes that did not pass the milspec requirements. A small surveillance scope intended primarily for Law Enforcement use, that is designed specifically to use surplus MX9644 tubes from AN/PVS-4s that are upgraded to Gen III tubes. A direct descendant of the AN/PVS-4 using an advanced Gen III+I F4844 Image tube, it

1998-513: Is an observation scope, although it does come with reticles and can be used as a weapon sight as well. With a larger catadioptric lens and higher zoom level, it is rated with a detection range of over 1 Kilometer with a third-generation image intensifier tube. The NVS-700 is the original designation of the Optic Electronics Corp. AN/PVS-4. This model is also manufactured in Iran. The NVS-800

2109-732: Is capable of identifying targets at ranges of up to seven kilometers. It is intended as the sighting mechanism for the Stinger missile. It features as 2.26x zoom and a 23.5 degree field of view. Military of the United States The United States Armed Forces are the military forces of the United States . The armed forces consist of six service branches : the Army , Marine Corps , Navy , Air Force , Space Force , and Coast Guard . All six armed services are among

2220-592: Is focus sweep. The focal plane is swept across the entire relevant range during a single exposure. This creates a blurred image, but with a convolution kernel that is nearly independent of object depth, so that the blur is almost entirely removed after computational deconvolution. This has the added benefit of dramatically reducing motion blur. Light Scanning Photomacrography (LSP) is another technique used to overcome depth of field limitations in macro and micro photography. This method allows for high-magnification imaging with exceptional depth of field. LSP involves scanning

2331-599: Is led by the chairman of the Joint Chiefs of Staff , who is the military head of the armed forces and principal advisor to the president and secretary of defense on military matters. Their deputy is the vice chairman of the Joint Chiefs of Staff . Other members include the chief of staff of the Army , commandant of the Marine Corps , chief of naval operations , chief of staff of the Air Force , chief of space operations , and

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2442-509: Is now one of the eight uniformed services of the United States. Should it be called into active duty again, it would constitute a seventh branch of the Armed Forces. The United States Space Force was established as an independent service on 20 December 2019. It is the sixth branch of the U.S. military and the first new branch in 72 years. The origin of the Space Force can be traced back to

2553-583: Is paramount. Other authors such as Ansel Adams have taken the opposite position, maintaining that slight unsharpness in foreground objects is usually more disturbing than slight unsharpness in distant parts of a scene. Some methods and equipment allow altering the apparent DOF , and some even allow the DOF to be determined after the image is made. These are based or supported by computational imaging processes. For example, focus stacking combines multiple images focused on different planes, resulting in an image with

2664-421: Is the transverse magnification which is the ratio of the lateral image size to the lateral subject size. Image sensor size affects DOF in counterintuitive ways. Because the circle of confusion is directly tied to the sensor size, decreasing the size of the sensor while holding focal length and aperture constant will decrease the depth of field (by the crop factor). The resulting image however will have

2775-679: Is the distance between the nearest and the farthest objects that are in acceptably sharp focus in the image. "Acceptably sharp focus" is defined using a property called the " circle of confusion ". The depth of field can be determined by focal length , distance to subject (object to be imaged), the acceptable circle of confusion size, and aperture. Limitations of depth of field can sometimes be overcome with various techniques and equipment. The approximate depth of field can be given by: DOF ≈ 2 u 2 N c f 2 {\displaystyle {\text{DOF}}\approx {\frac {2u^{2}Nc}{f^{2}}}} for

2886-563: Is the original des of the Optic Electronics Corp. AN/TVS-5. This model is also manufactured in Iran. Observation version of the AN/PVS-4 without a reticle, manufactured in Iran. Binocular version of AN/PVS-4 without reticle, manufactured in Iran. Individual Night Vision Sight, With Reticle, manufactured in Iran. Binocular Night Vision scope, based on AN/TVS-5, manufactured in Iran. AN/PVS-4 made in Israel by New Noga Light. AN/TVS-5 derivative made in Israel by New Noga Light. The Star-Tron 426

2997-513: Is the world's 12th-largest maritime force. The history of the U.S. Armed Forces dates back to 14 June 1775, with the creation of the Continental Army , even before the Declaration of Independence marked the establishment of the United States. The Continental Navy , established on 13 October 1775, and Continental Marines , established on 10 November 1775, were created in close succession by

3108-538: Is unique in that it is a military branch specializing in maritime operations and also a law enforcement agency. The United States Army (USA) is the United States Armed Forces' land force and is the largest and oldest service. Originally established in 1775 as the Continental Army , it consists of one million soldiers across the Regular Army, Army Reserve , and Army National Guard . The Army serves as

3219-459: The DOF will remain constant. For a given subject framing and camera position, the DOF is controlled by the lens aperture diameter, which is usually specified as the f-number (the ratio of lens focal length to aperture diameter). Reducing the aperture diameter (increasing the f-number ) increases the DOF because only the light travelling at shallower angles passes through the aperture so only cones of rays with shallower angles reach

3330-700: The 10th Mountain Division , 11th Airborne Division , 25th Infantry Division , 82nd Airborne Division , 101st Airborne Division , and 173rd Airborne Brigade have a cavalry squadron equipped with the Joint Light Tactical Vehicle . The Field Artillery's mission is to destroy, suppress or neutralize the enemy by cannon, rocket or missile fire. Rocket systems include the M142 HIMARS and M270 multiple launch rocket system , which are corps-level assets found in field artillery brigades. Towed artillery includes

3441-523: The 11th Airborne Division , 82nd Airborne Division , and 173rd Airborne Brigade are capable of airborne operations, in cooperation with the U.S. Air Force's transport aircraft. Finally, Infantry Brigade Combat Teams assigned to the 10th Mountain Division specialize in mountain warfare . Standard Infantry Brigade Combat Teams are assigned to the 25th Infantry Division , which offers additional training in jungle warfare . Armored Brigade Combat Teams comprise mechanized infantry battalions mounted in

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3552-400: The 4th Infantry Division . Each Armored Brigade Combat Team also possesses a cavalry squadron equipped with M2 Bradleys for scouting and security. Stryker Brigade Combat Teams from the 2nd Infantry Division , 4th Infantry Division , 11th Airborne Division , 2nd Cavalry Regiment , and 3rd Cavalry Regiment have a cavalry squadron equipped with Strykers . Infantry Brigade Combat Teams from

3663-507: The 75th Ranger Regiment are an elite special operations infantry force in the United States Army Special Operations Command , specializing in air assault and airborne infiltration methods. The three primary missions of the 75th Ranger Regiment are special operations raids , forcible entry operations, such as an airfield seizure to enable the Air Force to bring in more forces, and special reconnaissance . As

3774-713: The Air Force Space Command , which was formed 1 September 1982 and was a major command of the United States Air Force. The U.S. Congressional Research Office annually publishes a List of Notable Deployments of U.S. Military Forces Overseas since 1798. Presidential command over the U.S. Armed Forces is established in Article II in the Constitution whereby the president is named as the " Commander in Chief of

3885-579: The Department of the Navy , which is a military department under the leadership of the secretary of the Navy and the under secretary of the Navy . The U.S. Marine Corps itself is led by the commandant of the Marine Corps and the assistant commandant of the Marine Corps , both generals who are advised by the sergeant major of the Marine Corps . The Marine Corps statutory mission is outlined in 10 U.S.C.   § 5063 and as originally introduced under

3996-683: The FIM-92 Stinger man-portable air-defense system , AN/TWQ-1 Avenger for short range air defense , and the counter rocket, artillery, and mortar 20mm gun system. The Iron Dome provides air defense against rockets, artillery, mortars, missiles, and unmanned aerial vehicles. The MIM-104 Patriot is capable of defeating a wide range of threats including aircraft, helicopters, UAVs, ballistic and cruise missiles, and Weapons of Mass Destruction. The Terminal High Altitude Area Defense protects strategic critical assets by conducting long-range endo-and-exo-atmospheric engagements of ballistic missiles using

4107-600: The M119 howitzer in infantry brigade combat teams and the M777 howitzer found in both infantry and Stryker brigade combat teams. The M109 self-propelled howitzer is utilized in armored brigade combat teams. During the Cold War, Army field artillery was responsible for the service's ballistic missile programs, including the PGM-11 Redstone , which was the first large ballistic missile in

4218-660: The M2 Bradley infantry fighting vehicle . Divisions with Armored Brigade Combat Teams include the 1st Infantry Division , 3rd Infantry Division , 4th Infantry Division , 1st Armored Division , and 1st Cavalry Division . Stryker Brigade Combat Teams are centered around Stryker infantry battalions operating out of the Stryker . Divisions with Stryker Brigade Combat Teams include the 2nd Infantry Division , 4th Infantry Division , 11th Airborne Division , 2nd Cavalry Regiment , and 3rd Cavalry Regiment . United States Army Rangers with

4329-681: The MQ-1C Gray Eagle drone. A specialized unit within Army Aviation, the 160th Special Operations Aviation Regiment (Airborne) serves as a special operations unit and operates modified variants of the MH-60 Black Hawk, MH-47 Chinook, and the MH-6 Little Bird . The U.S. Army is organized into four major Army Commands, nine Army Service Component Commands which serve as the Army component and joint force land component commanders for

4440-519: The Marine Corps Reserve . The Marine Corps maintains a very close relationship with the U.S. Navy, its sister service in the Department of the Navy. Although the Marine Corps has previously operated as an independent land force alongside the Army, its primary purpose is to serve as part of a unified naval service alongside the Navy in the maritime domain. The U.S. Marine Corps is organized under

4551-480: The National Security Act of 1947 , with its three primary areas of responsibility including: Depth of field The depth of field ( DOF ) is the distance between the nearest and the farthest objects that are in acceptably sharp focus in an image captured with a camera . See also the closely related depth of focus . For cameras that can only focus on one object distance at a time, depth of field

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4662-769: The Second Continental Congress in order to defend the new nation against the British Empire in the American Revolutionary War . These forces demobilized in 1784 after the Treaty of Paris ended the Revolutionary War. The Congress of the Confederation created the current United States Army on 3 June 1784. The United States Congress created the current United States Navy on 27 March 1794 and

4773-539: The chief of the National Guard Bureau . The commandant of the Coast Guard is not an official member of the Joint Chiefs, but sometimes attends meetings as one of the military service chiefs. The senior enlisted advisor to the chairman is the most senior enlisted member in the United States Armed Forces. Leadership of the Armed Forces, to include the president of the United States, the secretary of defense ,

4884-523: The deputy secretary of defense , deputy secretary of homeland security , and vice chairman of the Joint Chiefs of Staff . Military leadership, including the secretary of defense, the secretary of Homeland Security, and chairman of the Joint Chiefs of Staff also sit on the National Space Council . Unified combatant commands are joint military commands consisting of forces from multiple military departments, with their chain of command flowing from

4995-425: The f-number that will give the maximum possible sharpness; Peterson's approach determines the minimum f-number that will give the desired sharpness in the final image and yields a maximum depth of field for which the desired sharpness can be achieved. In combination, the two methods can be regarded as giving a maximum and minimum f-number for a given situation, with the photographer free to choose any value within

5106-482: The hyperfocal distance , sometimes almost at infinity. For example, if photographing a cityscape with a traffic bollard in the foreground, this approach, termed the object field method by Merklinger, would recommend focusing very close to infinity, and stopping down to make the bollard sharp enough. With this approach, foreground objects cannot always be made perfectly sharp, but the loss of sharpness in near objects may be acceptable if recognizability of distant objects

5217-603: The joint force land component , Navy components are typically dual-hatted as the joint force maritime component , and Air Force components are typically dual-hatted as the joint force air component , with the theater special operations command dual-hatted as the joint force special operations component, and Space Force component typically dual-hatted as the joint force space component. Combat support agencies are Department of Defense agencies with combat support missions that service operating forces planning or conducting military operations. This includes support during conflict or in

5328-543: The secretary of Homeland Security and chairman of the Joint Chiefs of Staff are members of the United States National Security Council , which advises the president on national security, military, and foreign policy matters. The national security advisor , the homeland security advisor , and the deputy national security advisor may also be members of the United States Armed Forces. The National Security Council Deputies Committee also includes

5439-410: The sergeant major of the Army . The Army's primary responsibility is to conduct prompt and sustained land combat as part of the joint force. Army landpower focuses on destroying an enemy's armed forces, occupying its territory, and breaking the will of an adversary. The five core competencies of the Army are: The thirteen specified functions of the Army are: The Infantry Branch forms the core of

5550-523: The unified combatant commands , and thirteen direct reporting units. The United States Marine Corps (USMC) serves as the U.S. Armed Forces' naval land force, responsible for executing amphibious warfare and operating in the maritime littorals in support of the U.S. Navy. Originally established in 1775 as the Continental Marines , the Marine Corps consists of the Regular Marine Corps and

5661-546: The 1800s and are still in use today on view cameras, technical cameras, cameras with tilt/shift or perspective control lenses, etc. Swiveling the lens or sensor causes the plane of focus (POF) to swivel, and also causes the field of acceptable focus to swivel with the POF ; and depending on the DOF criteria, to also change the shape of the field of acceptable focus. While calculations for DOF of cameras with swivel set to zero have been discussed, formulated, and documented since before

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5772-539: The 1940s, documenting calculations for cameras with non-zero swivel seem to have begun in 1990. More so than in the case of the zero swivel camera, there are various methods to form criteria and set up calculations for DOF when swivel is non-zero. There is a gradual reduction of clarity in objects as they move away from the POF , and at some virtual flat or curved surface the reduced clarity becomes unacceptable. Some photographers do calculations or use tables, some use markings on their equipment, some judge by previewing

5883-440: The 1950s, it was not until the AN/PVS-4 was developed that a practical, high quality device that met military requirements was first made available. Unlike earlier passive starlight weapon scopes the AN/PVS-4 provided a high quality image without significant distortion, could adjust to changing ambient light conditions, was able to take multiple reticles to operate in many roles and had protective features allowing it to shut down in

5994-475: The ABC or Automatic Brightness Controls will reduce the gain, although the image may be too bright for the reticle to show correctly. When used, the image of the AN/PVS-4 is reduced and appears somewhat triangular. Due to the small apertures and resulting light diffraction, focusing behavior differs from normal operation due to the increased depth of field . In December 1974, the final AN/PVS-4 Development Test recorded

6105-559: The AN/PVS-4A use two common AA batteries (BA-3058/U) via a purpose-built adapter (PN A3009873) that attaches to one of the circular battery compartments. Use of the adapter negates the need for BA-5567/U and BA-3058/U. AN/PVS-4s still in use today are typically upgraded with the AA battery adapter even if they have not been upgraded to a third generation tube. Some AN/PVS-4A models made after 1984 feature an integral AA battery housing that does not require

6216-486: The Air Force through its Air and Missile Defense Commands and the Space Force through Army Space and Missile Defense Command, given their shared missile defense and space roles. In 1962, Air Defense Artillery achieved the first intercept of a ballistic missile with a nuclear-tipped Nike Zeus and operated the Nike Zeus as an anti-satellite weapon after completing a successful intercept in 1963. Army Aviation, distinct from

6327-416: The Armed Forces principal land service, responsible for conducting land warfare operations. The U.S. Army is organized under the Department of the Army , which is a military department under the leadership of the secretary of the Army and under secretary of the Army . The U.S. Army itself is led by the chief of staff of the Army and vice chief of staff of the Army , both generals who are advised by

6438-577: The Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States." The United States Armed Forces are split between two cabinet departments, with the Department of Defense serving as the primary cabinet department for military affairs and the Department of Homeland Security responsible for administering the United States Coast Guard . The military chain of command flows from

6549-624: The Department of Defense's military departments. The United States Coast Guard is nominally under the Department of Homeland Security , but may be transferred to the Department of Defense's Department of the Navy (which is the civilian entity that oversees the coequal U.S. Marine Corps and U.S. Navy) at the direction of the President or Congress. With the exception of the Coast Guard, the military services only organize, train, and equip forces. The unified combatant commands are responsible for operational control of non-service retained forces. Each of

6660-619: The MX-9644. The MX-9644 tube was also continued in the form of the MX9644/UV which was a second generation tube although evidence exists that a further hybrid tube (Gen3 tube attached by FO to a Gen1 tube) was developed under this specification to provide far more gain, improved S/N and lower EBI. Hybrid tubes are capable of gains well in excess of 100,000 times. The Stinger Night Sight is a good example of Gen3+1 technology. The ITT F4849 and ITT F4960 (MX-11619 and MX-11620) were also developed which use

6771-425: The Navy. The Air Force conducts air operations. The Space Force conducts space operations. The Coast Guard is unique in that it specializes in maritime operations and is also a law enforcement agency. From their inception during the American Revolutionary War , the U.S. Armed Forces have played a decisive role in the country's history . They helped forge a sense of national unity and identity through victories in

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6882-504: The President of the United States to the secretary of defense (for services under the Defense Department) or secretary of homeland security (for services under the Department of Homeland Security), ensuring civilian control of the military . Within the Department of Defense, the military departments ( Department of the Army , United States Department of the Navy , and Department of the Air Force ) are civilian led entities that oversee

6993-540: The Tube Brightness knob as low as possible. Although not specifically considered "variants" there are a number of other models that share the AN/PVS-4 lineage and often use interchangeable components, including the image intensifier tube. The addition of a "A" after the model, e.g., AN/PVS-4A, signifies a third-generation image intensifier tube and may be designated either after upgrade or at original manufacture. "A" variants typically use "AA" batteries. The AN/TVS-5

7104-482: The U.S. Air Force and its predecessors, began as part of the field artillery in 1942. Small spotter planes were used to spot for artillery and naval bombardment, as well as to perform observation. These few aircraft formed the core of Army Aviation once the U.S. Air Force gained independence. In 1983, the Army created the Aviation Branch, for the first time since the Air Force's independence consolidating aviation under

7215-708: The U.S. arsenal, the MGM-31 Pershing , and the Pershing II . In 2023, the Army is intending to field the Long-Range Hypersonic Weapon and has reestablished larger artillery formations like the 56th Artillery Command . The Air Defense Artillery is responsible for defending geopolitical assets and providing maneuver forces with the freedom to move on the battlefield by deterring the enemy and destroying aerial threats, missile attacks, and surveillance platforms. Weapons employed by Air Defense Artillery include

7326-477: The US military was still obtaining parts to both repair AN/PVS-4s and convert AN/PVS-4s to AN/TVS-5As. It is still presently also upgrading AN/PVS-4s to AN/PVS4As also. During the Gulf War , the AN/PVS-4 was widely deployed on a variety of weapons. The Gulf War represented the first war in which ground combat operations continued both day and night through the use of night vision devices . Although more modern equipment

7437-560: The United States is the United States Armed Forces' commander-in-chief . The United States Coast Guard traces its origin to the formation of the Revenue Cutter Service on 4 August 1790, which merged with the United States Life-Saving Service on 28 January 1915 to establish the Coast Guard. The United States Air Force was established as an independent service on 18 September 1947; it traces its origin to

7548-445: The act merged the cabinet-level departments of the Army, Navy, and Air Force into the DoD. The president of the U.S. is the commander-in-chief of the armed forces and forms military policy with the DoD and Department of Homeland Security (DHS), both federal executive departments , acting as the principal organs by which military policy is carried out. The U.S. Armed Forces are one of

7659-444: The blue channel may be f /5.6 . Therefore, the blue channel will have a greater depth of field than the other colours. The image processing identifies blurred regions in the red and green channels and in these regions copies the sharper edge data from the blue channel. The result is an image that combines the best features from the different f-numbers . At the extreme, a plenoptic camera captures 4D light field information about

7770-451: The brightness of the reticle to be adjusted. Elevation and Windage adjustment is made through turrets located on the objective lens. Each click equals 1/4 moa. The AN/PVS4 also has a Day/Night adapter that allows sighting in of the units during the day time or for daytime operation of the sight. Under extremely bright nighttime conditions, it may be necessary to use this adapter. The adapter consists of three hole sizes spaced evenly around

7881-442: The circle of confusion. The acceptable circle of confusion depends on how the final image will be used. The circle of confusion as 0.25 mm for an image viewed from 25 cm away is generally accepted. For 35   mm motion pictures, the image area on the film is roughly 22 mm by 16 mm. The limit of tolerable error was traditionally set at 0.05 mm (0.0020 in) diameter, while for 16 mm film , where

7992-410: The coequal military service branches organized within each department. The military departments and services are responsible for organizing, training, and equipping forces, with the actual chain of command flowing through the unified combatant commands . The Joint Chiefs of Staff , although outside the operational chain of command, is the senior-most military body in the United States Armed Forces. It

8103-444: The combined effects using the modulation transfer function . Many lenses include scales that indicate the DOF for a given focus distance and f-number ; the 35 mm lens in the image is typical. That lens includes distance scales in feet and meters; when a marked distance is set opposite the large white index mark, the focus is set to that distance. The DOF scale below the distance scales includes markings on either side of

8214-662: The conduct of other military activities related to countering threats to U.S. national security. This mission is focused on providing support to echelons at the CCMD level and below and may not encompass the full scope of the CSA's mission. The United States Armed Forces is composed of six coequal military service branches. Five of the branches, the United States Army , United States Marine Corps , United States Navy , United States Air Force , and United States Space Force , are organized under

8325-469: The current United States Marine Corps on 11 July 1798. All three services trace their origins to their respective Continental predecessors. The 1787 adoption of the Constitution gave Congress the power to "raise and support armies," to "provide and maintain a navy", and to "make rules for the government and regulation of the land and naval forces", as well as the power to declare war . The President of

8436-409: The difference v N − v F as the focus spread . If a subject is at distance s and the foreground or background is at distance D , let the distance between the subject and the foreground or background be indicated by x d = | D − s | . {\displaystyle x_{\mathrm {d} }=|D-s|.} The blur disk diameter b of

8547-401: The different military services is assigned a role and domain. The U.S. Army conducts land operations, while the U.S. Navy and U.S. Marine Corps conduct maritime operations, with the Marine Corps specializing in amphibious and maritime littoral operations in support of the Navy. The U.S. Air Force conducts air operations, while the U.S. Space Force conducts space operations. The U.S. Coast Guard

8658-604: The early-19th-century First and Second Barbary Wars . They played a critical role in the territorial evolution of the U.S. , including the American Civil War . The National Security Act of 1947 created the modern U.S. military framework, establishing the National Military Establishment (later the Department of Defense or DoD) headed by the secretary of defense and creating both the U.S. Air Force and National Security Council ; in 1949, an amendment to

8769-582: The effective absolute aperture diameter can be used for similar formula in certain circumstances. Moreover, traditional depth-of-field formulas assume equal acceptable circles of confusion for near and far objects. Merklinger suggested that distant objects often need to be much sharper to be clearly recognizable, whereas closer objects, being larger on the film, do not need to be so sharp. The loss of detail in distant objects may be particularly noticeable with extreme enlargements. Achieving this additional sharpness in distant objects usually requires focusing beyond

8880-496: The eight uniformed services of the United States , along with the U.S. Public Health Service Commissioned Corps and the NOAA Commissioned Officer Corps . Each of the different military services is assigned a role and domain. The Army conducts land operations. The Navy and Marine Corps conduct maritime operations, the Marine Corps specializing in amphibious and maritime littoral operations primarily for supporting

8991-477: The enemy's active device would be clearly observable to a anyone employing an AN/PVS-4, making the enemies position easily known. Reticle burn-in was also addressed. One issue that persists even in production models is the tendency for the projected reticle pattern to become washed out in bright light. This can be somewhat mitigated by adjusting the Reticle Brightness knob to its brightest position and keeping

9102-507: The event of exposure to bright light, but still recover in time after a muzzle flash for the operator to see the round hit the target. Using the MX-9644 Image Intensifier tube the AN/PVS-4 became one of the most widely used night vision scopes and has been in active use for more than a quarter of a century. Initial engineering development of the AN/PVS-4 was undertaken by Optic Electronic Corporation of Dallas, Texas, in 1975 as

9213-505: The first to derive a formula for hyperfocal distance. Rudolf Kingslake wrote in 1951 about the two methods of measuring hyperfocal distance. The DOF beyond the subject is always greater than the DOF in front of the subject. When the subject is at the hyperfocal distance or beyond, the far DOF is infinite, so the ratio is 1:∞; as the subject distance decreases, near:far DOF ratio increases, approaching unity at high magnification. For large apertures at typical portrait distances,

9324-453: The force around the world, including around 800 military bases outside the U.S. The U.S. Air Force is the world's largest air force, followed by the U.S. Army Aviation Branch . The U.S. Naval Air Forces is the fourth-largest air arm in the world and is the largest naval aviation service, while U.S. Marine Corps Aviation is the world's seventh-largest air arm. The U.S. Navy is the world's largest navy by tonnage . The U.S. Coast Guard

9435-584: The formation of the Aeronautical Division, U.S. Signal Corps , which was formed 1 August 1907 and was part of the Army Air Forces before being recognized as an independent service in the National Security Act of 1947. The United States Public Health Service Commissioned Corps was formerly considered to be a branch of the United States Armed Forces from 29 July 1945 until 3 July 1952, and

9546-445: The image and could be retrofitted to driving scopes that also used this tube. Operation of the device is through two controls located on the left side of the tube housing. The lower control is an on/off switch for the image intensifier tube and secondarily controls the gain of the tube, allowing the operator to control the brightness of the image. The upper control is an on/off switch for the illuminated reticle and secondarily allows

9657-407: The image plane. In other words, the circles of confusion are reduced or increasing the DOF . For a given size of the subject's image in the focal plane, the same f-number on any focal length lens will give the same depth of field. This is evident from the above DOF equation by noting that the ratio u / f is constant for constant image size. For example, if the focal length is doubled,

9768-450: The image. When the POF is rotated, the near and far limits of DOF may be thought of as wedge-shaped, with the apex of the wedge nearest the camera; or they may be thought of as parallel to the POF . Traditional depth-of-field formulas can be hard to use in practice. As an alternative, the same effective calculation can be done without regard to the focal length and f-number . Moritz von Rohr and later Merklinger observe that

9879-451: The index that correspond to f-numbers . When the lens is set to a given f-number , the DOF extends between the distances that align with the f-number markings. Photographers can use the lens scales to work backwards from the desired depth of field to find the necessary focus distance and aperture. For the 35 mm lens shown, if it were desired for the DOF to extend from 1 m to 2 m, focus would be set so that index mark

9990-413: The loss from diffraction. However, diffraction is a greater issue in close-up photography, and the overall image sharpness can be degraded as photographers are trying to maximize depth of field with very small apertures. Hansma and Peterson have discussed determining the combined effects of defocus and diffraction using a root-square combination of the individual blur spots. Hansma's approach determines

10101-663: The most versatile special operations force in the entire world, operating as a multi-purpose force since 1952. The Armor Branch traces its history back to the United States Cavalry and are responsible for tank and cavalry reconnaissance operations. The U.S. Army fields the M1 Abrams main battle tank in Armored Battalions as part of Armored Brigade Combat Teams across the 1st Armored Division , 1st Cavalry Division , 1st Infantry Division , 3rd Infantry Division , and

10212-510: The optical requirements of any night vision device that used it. Although not a hybrid tube (Gen1 and Gen2 in the same tube housing) it nonetheless produced a gain of around 20,000 making it suitable for use under starlight only conditions and even overcast starlight conditions in remote locations. The MX-9644 was later replaced by the MX-11620 Third-generation tube, which is a direct replacement for devices that were designed to use

10323-412: The periphery These pass by three larger aperture holes and three dark glass lenses to allow for six different levels of light reduction into the scope. As a result, the AN/PVS-4 can be used in lighting conditions ranging from midday-sun in the desert, through to very-bright-moonlight and high levels of urban lighting. Under moonlight or lower conditions, the AN/PVS-4 can be used without the adaptor and

10434-438: The president, to the secretary of defense, to the commanders of the combatant commands. Each service organizes, trains, and equips forces that are then presented to the unified combatant commands through service component commands. Special Operations Command and Cyber Command also present theater special operations commands or joint force headquarters – cyber to other combatant commanders. Army components are typically dual-hatted as

10545-441: The range, as conditions (e.g., potential motion blur) permit. Gibson gives a similar discussion, additionally considering blurring effects of camera lens aberrations, enlarging lens diffraction and aberrations, the negative emulsion, and the printing paper. Couzin gave a formula essentially the same as Hansma's for optimal f-number , but did not discuss its derivation. Hopkins, Stokseth, and Williams and Becklund have discussed

10656-425: The ratio is still close to 1:1. This section covers some additional formula for evaluating depth of field; however they are all subject to significant simplifying assumptions: for example, they assume the paraxial approximation of Gaussian optics . They are suitable for practical photography, lens designers would use significantly more complex ones. For given near and far DOF limits D N and D F ,

10767-487: The required f-number is smallest when focus is set to s = 2 D N D F D N + D F , {\displaystyle s={\frac {2D_{\mathrm {N} }D_{\mathrm {F} }}{D_{\mathrm {N} }+D_{\mathrm {F} }}},} the harmonic mean of the near and far distances. In practice, this is equivalent to the arithmetic mean for shallow depths of field. Sometimes, view camera users refer to

10878-762: The service's land combat power. U.S. Army infantry are generally equipped with the M4 carbine and M249 light machine gun , which will be replaced by the XM7 rifle and XM250 . Infantry is a core part of the Army's Brigade Combat Teams . The most numerous variant, the Infantry Brigade Combat Team, comprises light infantry battalions who fight on foot. Infantry Brigade Combat Teams of the 82nd Airborne Division are air assault capable, with infantry soldiers being transported by U.S. Army Aviation UH-60 Black Hawk and CH-47 Chinook helicopters. Infantry Brigade Combat Teams of

10989-444: The sight was a common problem that was addressed. An example of a noted shortcoming ultimately considered insignificant was an enemies ability to detect the reflection of the AN/PVS-4 objective lens using an active infrared night vision device. The IR device needed to detect the AN/PVS-4 required a straight-on unobstructed view, and AN/PVS-4 detection only occurred using an active device (as opposed to passive). The IR light emitted from

11100-399: The size is about half as large, the tolerance is stricter, 0.025 mm (0.00098 in). More modern practice for 35 mm productions set the circle of confusion limit at 0.025 mm (0.00098 in). The term "camera movements" refers to swivel (swing and tilt, in modern terminology) and shift adjustments of the lens holder and the film holder. These features have been in use since

11211-806: The square of the distance to the subject and inversely in proportion to the square of the focal length. As a result, photos taken at extremely close range (i.e., so small u ) have a proportionally much smaller depth of field. Rearranging the DOF equation shows that it is the ratio between distance and focal length that affects DOF ; DOF ≈ 2 N c ( u f ) 2 = 2 N c ( 1 − 1 M T ) 2 {\displaystyle {\text{DOF}}\approx 2Nc\left({\frac {u}{f}}\right)^{2}=2Nc\left(1-{\frac {1}{M_{T}}}\right)^{2}} Note that M T = − f u − f {\textstyle M_{T}=-{\frac {f}{u-f}}}

11322-418: The subject distance is also doubled to keep the subject image size the same. This observation contrasts with the common notion that "focal length is twice as important to defocus as f/stop", which applies to a constant subject distance, as opposed to constant image size. Motion pictures make limited use of aperture control; to produce a consistent image quality from shot to shot, cinematographers usually choose

11433-468: The use of an external AA battery adapter. Much of the success and longevity of the AN/PVS-4 was due to the MX-9644 Image Intensifier tube. To make the tube more usable with simple optics, a second-generation MCP based image intensifier was adapted to an electrostatic inverter, similar to a first-generation image intensifier. The result was that the tube produced an inverted image, simplifying

11544-452: The various shortcomings found during field testing. The majority of the issues were addressed in final production. Issues not addressed were deemed permissible. Several issues noted were reliability, specifically with intensifier tubes being damaged due to moisture. This problem was fully addressed in final production. It was also noted the mount designed to secure the AN/PVS-4 to the M60 machine gun

11655-536: The way of resolution. Two other tube developments that occurred but were not widely manufactured included optical relays to invert the image both in front and behind a Gen3 25mm tube. This allowed for significant increases in tube resolution and performance over the FO based third generation tubes and involved a lens assembly being housed in a container that matched the MX-9644 tube exactly. Related development for driving based devices included Fiber Optic expanders that magnified

11766-410: The world's largest military forces in terms of personnel. They draw their personnel from a large pool of professional volunteers . The U.S. has used military conscription , but not since 1973. The Selective Service System retains the power to conscript males, requiring the registration of all male citizens and residents of the U.S. between the ages of 18 and 25. The U.S. Armed Forces are considered

11877-506: The world's largest air-transportable X-band radar. The Ground-Based Midcourse Defense is an anti-ballistic missile system operated by Army Space and Missile Defense Command to defend the United States homeland against an intercontinental ballistic missile attack. Major Air Defense Artillery units include the 32nd Army Air and Missile Defense Command and Army Space and Missile Defense Command's 100th Missile Defense Brigade . Air Defense Artillery has an extremely close relationship with

11988-490: The world's most powerful military, especially since the end of the Cold War . The military expenditure of the U.S. was US$ 916 billion in 2023, the highest in the world, accounting for 37% of the world's defense expenditures . The U.S. Armed Forces has significant capabilities in both defense and power projection due to its large budget, resulting in advanced and powerful technologies which enable widespread deployment of

12099-651: Was available during the Iraq War , the AN/PVS-4 was still in active use. Production of the AN/PAS-13 thermal weapon sight began in 1996 and production of the AN/PVS-4 ceased entirely by 2002. The AN/PVS-4 uses a 25mm screw-type variable-gain Image Intensifier tube. Operational voltage is 3.0 Volts. Early production models feature two circular battery compartments located on the main housing. These battery compartments are designed to accommodate one 3.0V BA-5567/U, or two 1.5V BA-3058/U simultaneously. Later designations such as

12210-421: Was centered between the marks for those distances, and the aperture would be set to f /11 . On a view camera, the focus and f-number can be obtained by measuring the depth of field and performing simple calculations. Some view cameras include DOF calculators that indicate focus and f-number without the need for any calculations by the photographer. In optics and photography , hyperfocal distance

12321-558: Was difficult to install and prone to loss of zero. The sight reticles for both the M16 rifle and M14 rifle required firing a minimum of 20 rounds to seat before the zeroing procedures could begin, leading to an excessive expenditure of ammunition. The sight reticles were subsequently modified, requiring only 2 rounds for seating purposes. Early reticles for the M16/M203 could not be zeroed for each weapon simultaneously. Rubber eye guard separation from

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