Binocular telescopes, or binoculars, (also known as field glasses) are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. Symmetry generally conveys two primary meanings The first is an imprecise sense of harmonious or aesthetically-pleasing proportionality and balance such that it reflects beauty or An optical telescope is a Telescope which is used to gather and focus light mainly from the visible part of the Electromagnetic spectrum Binocular vision is vision in which both Eyes are used together Most are sized to be held using both hands, although there are much larger types.

Unlike a monocular telescope, a binocular gives users a three-dimensional image: the two views, presented from slightly different viewpoints to each of the viewer's eyes, produce a merged view with depth perception. A monocular is a modified Refracting telescope used to Magnify the images of distant objects by passing light through a series of lenses and prisms Depth perception is the visual ability to perceive the world in three Dimensions Although any animal capable of moving around its environment must be able to There is no need to close or obstruct one eye to avoid confusion, as is usual with monocular telescopes.

Contents 1 Optical design 1.1 Galilean binoculars 1.2 Porro prism binoculars 1.3 Roof prism binoculars 1.4 Porro vs. Roof prisms 2 Optical parameters 3 Optical coatings 4 Mechanical design 4.1 Focusing and adjustment 4.2 Image stabilization 4.3 Alignment 5 Applications 5.1 General use 5.2 Military 5.3 Astronomical 6 Manufacturers 6.1 Germany 6.2 Austria 6.3 Japan 6.4 China 6.5 United States 6.6 Russia 7 See also 8 Notes 9 References 10 External links

Optical design

Galilean binoculars

Almost from the invention of the telescope in the 17th century the advantages of mounting two of them side by side for binocular vision seems to have been explored^[1]. Most early binoculars used Galilean optics; that is they used a convex objective and a concave eyepiece lens. A refracting or refractor telescope is a dioptric Telescope that uses a lens as its objective to form an image A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging The Galilean design has the advantage of presenting an erect image but has a narrow field of view and is not capable of very high magnification. An erect image, in Optics, is one that appears right-side up Some Telescopes and other devices such as the Camera obscura present an upside down image This type of construction is still used in very cheap models and in "opera glasses" or theater glasses. Opera glasses, also known as theater binoculars or Galilean binoculars, are compact low-power optical magnification devices usually used at performance events whose

Porro prism binoculars

Named after Italian optician Ignazio Porro who patented this image erecting system in 1854 and later refined by makers like Carl Zeiss in the 1890s^[1], binoculars of this type use a Porro prism in a double prism Z-shaped configuration to erect the image. Ignazio Porro ( November 25 1801 - October 8 1875) was an Italian Inventor of Optical instruments. Carl Zeiss ( September 11, 1816 &ndash December 3, 1888) was an Optician commonly known for the company he founded Carl Zeiss In Optics, a Porro prism, named for its inventor Ignazio Porro, is a type of reflection prism used in optical instruments to alter the orientation This feature results in binoculars that are wide, with objective lenses that are well separated but offset from the eyepieces. For the device for looking through a camera see Viewfinder. An eyepiece, or ocular lens, is a type of lens that is attached Porro prism designs have the added benefit of folding the optical path so that the physical length of the binoculars is less than the focal length of the objective and wider spacing of the objectives gives better sensation of depth. The focal length of an optical system is a measure of how strongly it converges (focuses or diverges (diffuses Light.

Roof prism binoculars

Binoculars using Roof prisms may have appeared as early as the 1880s in a design by Achille Victor Emile Daubresse^{[2] [3]}. A roof prism (also called a Dach prism is in general any kind of reflective optical prism containing a section where two faces meet at a 90° angle Most roof prism binoculars use either the Abbe-Koenig prism (named after Ernst Karl Abbe and Albert Koenig and patented by Carl Zeiss in 1905)^[4] or Schmidt-Pechan prism (invented in 1899) designs to erect the image and fold the optical path. An Abbe-Koenig prism is a type of reflecting prism used to invert an image (rotate it by 180° Ernst Karl Abbe ( January 23, 1840 &ndash January 14, 1905) was a German Physicist and professor at the University A Schmidt-Pechan prism is a type of optical prism used to rotate an image by 180°. They have objective lenses that are approximately in line with the eyepieces.

Porro vs. Roof prisms

Roof-prisms designs create an instrument that is narrower and more compact than Porro prisms. There is also a difference in image brightness. Porro-prism binoculars will inherently produce a brighter image than roof-prism binoculars of the same magnification, objective size, and optical quality, because the roof-prism design employs silvered surfaces that reduce light transmission by 12% to 15%. In Optics, a Porro prism, named for its inventor Ignazio Porro, is a type of reflection prism used in optical instruments to alter the orientation A roof prism (also called a Dach prism is in general any kind of reflective optical prism containing a section where two faces meet at a 90° angle Roof-prisms designs also require tighter tolerances as far as alignment of their optical elements (collimation). Collimated light is Light whose rays are nearly parallel and therefore will spread slowly as it propagates This adds to their expense since the design requires them to use fixed elements that need to be set at a high degree of collimation at the factory. Porro prisms binoculars occasionally need their prism sets to be re-aligned to bring them into collimation. The fixed alignment in roof-prism designs means the binoculars normally won't need re-collimation^[5].

Optical parameters

Binoculars are usually designed for the specific application for which they are intended. Those different designs create certain optical parameters (some of which may be listed on the prism cover plate of the binocular). Those parameters are:

Magnification — The ratio of the focal length of the eyepiece divided into the focal length of the objective gives the linear magnifying power of binoculars (sometimes expressed as "diameters"). Magnification is the process of enlarging something only in appearance not in physical size A magnification of factor 7, for example, produces an image as if one were 7 times closer to the object. The amount of magnification depends upon the application the binoculars are designed for. Hand-held binoculars have lower magnifications so they will be less susceptible to shaking. A larger magnification leads to a smaller field of view.

Objective diameter – The diameter of the objective lens determines how much light can be gathered to form an image. An objective in Optics is the lens or Mirror in a Microscope, Telescope, camera or other optical instrument Geometry, a diameter of a Circle is any straight Line segment that passes through the center of the circle and whose Endpoints are on the It is usually expressed in millimeters.

It is customary to categorize binoculars by the magnification × the objective diameter; e. g. 7×50.

Field of view — The field of view of a binocular is determined by its optical design. The field of view (also field of vision) is the angular extent of the observable world that is seen at any given moment It is usually notated in a linear value, such as how many feet (meters) in width will be seen at 1,000 yards (or 1,000 m), or in an angular value of how many degrees can be viewed. The word linear comes from the Latin word linearis, which means created by lines. In Geometry and Trigonometry, an angle (in full plane angle) is the figure formed by two rays sharing a common Endpoint, called

Exit pupil — Binoculars concentrate the light gathered by the objective into a beam, the exit pupil, whose diameter is the objective diameter divided by the magnifying power. In Optics, the exit pupil is a virtual Aperture in an optical system For maximum effective light-gathering and brightest image, the exit pupil should equal the diameter of the fully dilated iris of the human eye— about 7 mm, reducing with age. The iris consists of Pigmented Fibrovascular tissue known as a stroma. Light gathered by a larger exit pupil is wasted. For daytime use an exit pupil of 3 mm—matching the eye's contracted pupil—is sufficient. However, a larger exit pupil makes alignment of the eye easier and avoids dark vignetting intruding from the edges. In Photography and Optics, vignetting is a reduction of an image's brightness or saturation at the Periphery compared to the image center

Eye relief — Eye relief is the distance from the rear eyepiece lens to where the image is formed. The eye relief of a Telescope, a Microscope, or Binoculars is the distance from the last surface of an Eyepiece at which the eye can be placed It determines the distance the observer must position his or her eye behind the eyepiece in order to see an unvignetted image. The longer the focal length of the eyepiece, the greater the eye relief. Binoculars may have eye relief ranging from few millimeters to 2. 5 centimeters or more. Eye relief can be particularly important for eyeglass wearers. The eye of an eyeglass wearer is typically further from the eye piece which necessitates a longer eye relief in order to still see the entire field of view. Binoculars with short eye relief can also be hard to use in instances where it is difficult to hold them steady.

Optical coatings

Main article: Anti-reflective coating

Since a binocular can have 16 air-to-glass surfaces, with light lost at every surface, optical coatings can significantly affect image quality. When light strikes an interface between two materials of different refractive index (e. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium g. , at an air-glass interface), some of the light is transmitted, some reflected. In Optics and Spectroscopy, transmittance is the fraction of incident light at a specified Wavelength that passes through a sample Reflection is the change in direction of a Wave front at an interface between two different media so that the wave front returns into the medium from which In any sort of image-forming optical instrument (telescope, camera, microscope, etc. ), ideally no light should be reflected; instead of forming an image, light which reaches the viewer after being reflected is distributed in the field of view, and reduces the contrast between the true image and the background. Reflection can be reduced, but not eliminated, by applying optical coatings to interfaces. Each time light enters or leaves a piece of glass; about 5% is reflected back. This "lost" light bounces around inside the binocular, making the image hazy and hard to see. Lens coatings effectively lower reflection losses, which finally results in a brighter and sharper image. For example, 8x40 binoculars with good optical coatings will yield a brighter image than uncoated 8x50 binoculars. Light can also be reflected from the interior of the instrument, but it is simple to minimize this to negligible proportions. Contrast is also improved by good coating due to the partial elimination of internal reflections.

A classic lens-coating material is magnesium fluoride; it reduces reflections from 5% to 1%. Magnesium fluoride (MgF2 is a white crystalline Salt composed of one Magnesium Ion and two Fluoride ions and is used in the Modern lens coatings consist of complex multi-layers and reflect only 0. 25% or less to yield an image with maximum brightness and natural colors. For roof-prisms, anti-phase shifting coatings are sometimes used which significantly improve contrast. The presence of a coating is typically denoted on binoculars by the following terms:

• coated optics: one or more surfaces coated.
• fully coated: all air-to-glass surfaces coated. Plastic lenses, however, if used, may not be coated.
• multi-coated: one or more surfaces are multi-layer coated.
• fully multi-coated: all air-to-glass surfaces are multi-layer coated.

Phase-corrected prism coating and dielectric prism coating are recent (in 2005) effective techniques for reducing reflections.

Mechanical design

Focusing and adjustment

Binoculars to be used to view objects that are not at a fixed distance must have a focusing arrangement. Focusing is a naturally occurring human process carefully observed and made teachable by philosopher and psychotherapist Eugene Gendlin. Traditionally, two different arrangements have been used to provide focus. Binoculars with "independent focus" require the two telescopes to be focused independently by adjusting each eyepiece, thereby changing the distance between ocular and objective lenses. Binoculars designed for heavy field use, such as military applications, traditionally have used independent focusing. Because general users find it more convenient to focus both tubes with one adjustment action, a second type of binocular incorporates "central focusing", which involves rotation of a central focusing wheel. In addition, one of the two eyepieces can be further adjusted to compensate for differences between the viewer's eyes (usually by rotating the eyepiece in its mount). This is known as a diopter. Once this adjustment has been made for a given viewer, the binoculars can be refocused on an object at a different distance by using the focusing wheel to move both tubes together without eyepiece readjustment.

There are also "focus-free" or "fixed-focus" binoculars. They have a depth of field from a relatively large closest distance to infinity, and perform exactly the same as a focusing model of the same optical quality (or lack of it) focused on the middle distance.

Zoom binoculars, while in principle a good idea, are generally considered not to perform very well. ^[6][7]

Most modern binoculars have hinged-telescope construction that enables the distance between eyepieces to be adjusted to accommodate viewers with different eye separation. This adjustment feature is lacking on many older binoculars.

Image stabilization

Shake can be much reduced, and higher magnifications used, with binoculars using image-stabilization technology. Image stabilization ( IS) is a family of techniques to increase the stability of an image Parts of the instrument which change the position of the image may be held steady by powered gyroscopes or by powered mechanisms driven by gyroscopic or inertial detectors, or may be mounted in such a way as to oppose and dampen sudden movement. A gyroscope is a device for measuring or maintaining orientation, based on the principles of Angular momentum. Stabilization may be enabled or disabled by the user as required. These techniques allow binoculars up to 20× to be hand-held, and much improve the image stability of lower-power instruments. There are some disadvantages: the image may not be quite as good as the best unstabilized binoculars when tripod-mounted, stabilized binoculars also tend to be more expensive and heavier than similarly specified non-stabilised binoculars.

Alignment

Well-collimated binoculars, when viewed through human eyes and processed by a human brain, should produce a single circular, apparently three-dimensional image, with no visible indication that one is actually viewing two distinct images from slightly different viewpoints. Departure from the ideal will cause, at best, vague discomfort and visual fatigue, but the perceived field of view will be close to circular anyway. The cinematic convention used to represent a view through binoculars as two circles partially overlapping in a figure-of-eight shape is not true to life.

Misalignment is remedied by small movements to the prisms, often by turning screws accessible without opening the binoculars, or by adjusting the position of the objective via eccentric rings built into the objective cell. An eccentric in Mechanical engineering is a circular disk ( eccentric sheave) solidly fixed to a rotating Axle with its centre offset from that of the axle Alignment is usually done by a professional although instructions for checking binoculars for collimation errors and for collimating them can be found on the Internet.

Applications

General use

Hand-held binoculars range from small 3 x 10 Galilean opera glasses, used in theaters, to glasses with 7 to 12 diameters magnification and 30 to 50 mm objectives for typical outdoor use. Opera glasses, also known as theater binoculars or Galilean binoculars, are compact low-power optical magnification devices usually used at performance events whose Theatre (or theater, see spelling differences) is the branch of the Performing arts defined by Bernard Beckerman as what "occurs when one Porro prism models predominate although bird watchers and hunters tend to prefer, and are prepared to pay for, the lighter but more expensive roof-prism models. Birdwatching or birding is the observation and study of Birds with the naked eye or through a visual enhancement device like Binoculars. Hunting is the practice of pursuing Animals for Food, Recreation, or Trade.

Many tourist attractions have installed pedestal-mounted, coin-operated binoculars to allow visitors to obtain a closer view of the attraction. A tourist attraction is a place of interest where Tourists visit typically for its inherent or exhibited cultural value historical significance natural or built beauty or In the United Kingdom, 20 pence often gives a couple of minutes of operation, and in the United States, one or two quarters gives between one-and-a-half to two-and-a-half minutes. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located A penny (pl pence or pennies) is a Coin or a unit of Currency used in several English -speaking countries The United States of America —commonly referred to as the A quarter dollar is a coin worth 1/4 of a United States dollar, or 25 cents.

Military

Binoculars have a long history of military use. Galilean designs were widely used up to the end of the 19th century when they gave way to porro prism types. Binoculars constructed for general military use tend to be more heavily ruggedized than their civilian counterparts. They generally avoid more fragile center focus arrangements in favor of independent focus. Prism sets in military binoculars may have redundant aluminized coatings on their prism sets to guarantee they don’t lose their reflective qualities if they get wet. Military binoculars of the cold war era were sometimes fitted with passive sensors that detected active IR emissions, while modern ones usually are fitted with filters blocking laser beams. Cold War is the state of conflict tension and competition that existed between the United States and the Soviet Union (USSR and their respective allies from the Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of Further, binoculars designed for military usage may include a stadiametric reticle in one ocular in order to facilitate range estimation. Stadiametric rangefinding, or the stadia method is a technique of measuring distances with a telescopic instrument.

There are binoculars designed specifically for civilian and military use at sea. Hand held models will be 5× to 7× but with very large prism sets combined with eyepieces designed to give generous eye relief. This optical combination prevents the image vignetting or going dark when the binocular is pitching and vibrating relative to the viewer's eye. Large, high-magnification, models with large objectives are also used in fixed mountings.

Very large binocular naval rangefinders (up to 15 meters separation of the two objective lenses, weight 10 tons, for ranging World War II naval gun targets 25 km away) have been used, although late-20th century technology made this application redundant. A rangefinder is a device that measures distance from the observer to a target for the purposes of Surveying, determining focus in Photography, or World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including

Astronomical

Binoculars are widely used by amateur astronomers; their wide field of view making them useful for comet and supernova seeking (giant binoculars) and general observation (portable binoculars). Amateur astronomy, a subset of Astronomy, is a Hobby whose participants enjoy studying and observing celestial objects The field of view (also field of vision) is the angular extent of the observable world that is seen at any given moment A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — A supernova (plural supernovae or supernovas) is a stellar Explosion. The Galilean moons of Jupiter, Ceres, Neptune, Pallas and Titan are invisible to the naked eye but can readily be seen with binoculars. The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei. Ceres (ˈsɪəriːz Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. TemplateInfobox Planet. --> 2 Pallas (ˈpæləs, or as Παλλάς) is one of the largest TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as The naked eye is a Figure of speech referring to human Visual perception that is unaided by enhancing equipment such as a Telescope or Although technically visible unaided in pollution-free skies, Uranus and Vesta require binoculars for practical observation. Air pollution is the human introduction into the atmosphere of Chemicals Particulate matter, or Biological materials that cause harm or discomfort TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt 10×50 binoculars are limited to a magnitude of around +9. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 5, which means asteroids like Interamnia, Davida, Europa and, except under exceptional conditions Hygiea, are too faint to be seen with binoculars. TemplateInfobox Planet. --> 704 Interamnia (ˌɪntərˈæmniə in'-tər-am'-nee-ə from Latin TemplateInfobox Planet. --> 511 Davida (dəˈviːdə də-VEE-də is a large TemplateInfobox Planet. --> 52 Europa (jʊˈroʊpə is an Asteroid. Likewise too faint to be seen with binoculars are all moons except the Galileans and Titan, and the dwarf planets Pluto and Eris. A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded

Of particular relevance for low-light and astronomical viewing is the ratio between magnifying power and objective lens diameter. A ratio is an expression which compares quantities relative to each other A lower magnification facilitates a larger field of view which is useful in viewing large deep sky objects such as the Milky Way, nebula, and galaxies, though the large exit pupil means some of the gathered light is wasted. Deep sky or Deep Sky Object (DSO for short which differs from Deep space, is a term used by amateur astronomers to describe mostly faint Astronomical objects outside The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Γαλαξίας (Galaxias sometimes referred to simply A nebula (from Latin: "mist" pl nebulae or nebulæ, with ligature or nebulas) is an Interstellar cloud of A galaxy is a massive gravitationally bound system consisting of Stars an Interstellar medium of gas and dust, and Dark matter The large exit pupil will also image the night sky background, effectively decreasing contrast, making the detection of faint objects more difficult except perhaps in remote locations with negligible light pollution. Light pollution, also known as photopollution or luminous pollution, is excess or obtrusive Light created mainly by Humans Among other effects Binoculars specifically for most astronomical uses have higher magnification and a larger aperture objective (in the 70mm or 80mm range) because the diameter of the objective lens determines the faintest star that can be observed. These binoculars usually require some sort of mount

Much larger binoculars have been made by amateur telescope makers, essentially using two refracting or reflecting astronomical telescopes, with mixed results. The field of amateur telescope making is considered an offshoot of the Amateur astronomy community A very large professional instrument, although not one that would normally be called binoculars, is the Large Binocular Telescope in Arizona, USA, which produced its "First Light" image on October 26, 2005. The Large Binocular Telescope ( LBT, originally named the Columbus Project) is located on 10700-foot Mount Graham in the Pinaleno Mountains Events 740 - An Earthquake strikes Constantinople, causing much damage and death Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. The LBT comprises two 8-meter reflector telescopes. While obviously not intended to be held to the eyes of a viewer, it uses two telescopes to view the same object, giving higher resolving power than a single instrument of the same light-gathering power, and allowing interferometric use. Interferometry is the technique of using the pattern of Interference created by the superposition of two or more Waves to diagnose the properties of

Manufacturers

Some notable binocular manufacturers as of 2008:

Germany

• Leica GmbH – Ultravid, Duovid, Geovid: all are roof prism.
• Optolyth – Royal, ViaNova: roof prism; Alpin, Alpin Classic: porro prism.
• Zeiss GmbH – FL, Victory, Conquest: roof prism; 7×50 BGAT/T porro, 15×60 BGA/T porro, discontinued.
• Eschenbach Optik GmbH – Farlux, Trophy, Adventure, Sektor. . . : some are roof prism, some porro.
• Docter (the former Carl Zeiss Jena plant in Eisfeld) Nobilem 7×50, 8×56, 10×50, 15×60: porro; Docter 7×40, 8×40, 10×40: roof prism.
• Steiner GmbH – Commander, Nighthunter: porro; Predator, Wildlife: roof prism.

Austria

• Delta Optical – binoculars, riflescopes, microscopes
• Swarovski Optik – SLC, EL: roof prism; Habicht: porro prism, but to be discontinued. Swarovski is the luxury Brand name for the range of precision-cut Lead crystal Glass and related products produced by companies owned by
• Minox
• Optolyth – Royal: Roof; Alpin: porro
• KAHLES – riflescopes, binoculars

Japan

• Canon Inc. – I. is a Japanese Multinational corporation that specializes in imaging and optical products including Cameras photocopiers and Computer printers S. series: porro variants?
• Nikon Co. – High Grade series, Monarch series, RAII, Spotter series: roof prism; Prostar series, Superior E series, E series, Action EX series: porro. ( also known as Nikon or Nikon Corp, is a Multinational corporation headquartered in Tokyo Japan specializing in Optics
• Fujinon Co. – FMTSX, FMTSX-2, MTSX series: porro. Fujinon is a division of Fujifilm that specialises in the production of optical lenses for photographic medical video and television use
• Kowa Co. – BD series: Roof prism.
• Pentax Co. – DCFSP/XP series: roof prism; UCF series: inverted porro; PCFV/WP/XCF series: porro. is a wholly owned division and brand name of Hoya Corporation.
• Olympus Co. – EXWPI series: roof prism. ( is a Japanese company specializing in Optics and Imaging. Olympus was established on October 12 1919 initially specialized in microscope
• Vixen Co. – Apex/Apex Pro: roof prism; Ultima: porro*
• Zenith
• Miyauchi Co. Vixen is a Japanese company that makes Telescopes Binoculars, Spotting scopes and accessories for their products In broad terms the zenith is the direction pointing directly above a particular location ( Perpendicular, Orthogonal) – specializes in oversized porro binoculars.

* Also sells OEM products manufactured by the Kamakura Koki Co. An original equipment manufacturer, or OEM is typically a company that uses a component made by a second company in its own product or sells the product of the second company Ltd. of Japan.

China

In the early 21st century, some mid-priced binoculars have become available in the internal Chinese market. A few are said to be comparable in both performance and price to those of some of the better brands, but the great majority are inferior.

• Sicong (from Xian Stateoptics) – Navigator series: roof prism; Ares series: porro.
• WDtian (from Yunnan State optics) – porro.
• Yunnan State optics – MS series: porro.

United States

• Alpen*
• Barska
• Brunton, Inc.
• Bushnell Performance Optics*
• Carson Optical
• Leupold & Stevens, Inc.*
• Simmons Optics
• Vortex Optics
• Weaver
• William Optics
• Zen-Ray Optics – SUMMIT, Vista Series WP. Brunton Inc is a manufacturer of technical gear for outdoor activity located in Riverton Wyoming Bushnell Corporation also known as Bushnell and Bushnell Outdoor Products is an American company specializing in Optics and Imaging. Vortex Optics is an American company developing optics for Hunting, Bird watching, wildlife watching, outdoor recreational sports and law

* Also sells OEM products manufactured by the KAMAKURA KOKI CO. An original equipment manufacturer, or OEM is typically a company that uses a component made by a second company in its own product or sells the product of the second company LTD. of Japan.

Russia

• Yukon Advanced Optics
• Baigish
• Kronos
• Russian Military Binoculars – BPOc 10x42 7x30, BKFC series.

See also

• Anti-fogging treatment of optical surfaces
• Binoviewer

Notes

References

• Nightskyinfo. com, A Guide to Binoculars, Emil Neata
• The history of the telescope & the binocular, The First 300 Years of Binocular Telescopes, Peter Abrahams, May 2002

External links

• A Guide to Binoculars

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