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Hyperfocal Distance
In optics and photography, hyperfocal distance is a distance 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 a lens focused at an object whose distance 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 extend from ''H''/3 to ''H''; if the lens is then focused to ''H''/3, the depth of field will extend 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 the first to derive a formula for hyperfocal distance. Rudo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minox LX Hyperfocal
Minox (pronounced ) is a manufacturer of cameras, known especially for its subminiature camera. The first product to carry the Minox name was a subminiature camera, conceived in 1922, and finally invented and produced in 1936, by Baltic German Walter Zapp. The Latvian factory VEF (''Valsts elektrotehniskā fabrika'') manufactured the camera from 1937 to 1943. After World War II, the camera was redesigned and production resumed in Germany in 1948. Walter Zapp originally envisioned the Minox to be a camera for everyone requiring only little photographic knowledge. Yet in part due to its high manufacturing costs the Minox became more well known as a must-have luxury item. From the start the Minox also gained wide notoriety as a spy camera. Minox branched out into 35 mm film format and 110 film format cameras in 1974 and 1976, respectively. Minox continues to operate today, producing or branding optical and photographic equipment. History From 1936 to 1975, the history of the M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focal Length
The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light. A system with a shorter focal length bends the rays more sharply, bringing them to a focus in a shorter distance or diverging them more quickly. For the special case of a thin lens in air, a positive focal length is the distance over which initially collimated (parallel) rays are brought to a focus, or alternatively a negative focal length indicates how far in front of the lens a point source must be located to form a collimated beam. For more general optical systems, the focal length has no intuitive meaning; it is simply the inverse of the system's optical power. In most photography and all telescopy, where the subject is essentially infinitely far away, longer focal length (lower opti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depssi
The Depssi card (Depth of field, sunrise, sunset indicator) is a handy guide/reference card that has two functions; it enables the outdoor photographer to quickly select the hyperfocal distance for different lenses (or zoom settings) using various aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...s. On the reverse side of the card there are the angles/positions of sunrise and sunset for every month. The card is made in a durable plastic suitable for prolonged use. The size of a credit card, it can be tucked into a wallet/purse or secured to your camera bag until needed. References {{photography-stub Photography equipment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deep Focus
Deep focus is a photographic and cinematographic technique using a large depth of field. Depth of field is the front-to-back range of focus in an image, or how much of it appears sharp and clear. In deep focus, the foreground, middle ground, and background are all in focus. Deep focus is normally achieved by choosing a small aperture. Since the aperture of a camera determines how much light enters through the lens, achieving deep focus requires a bright scene or long exposure. A wide-angle lens also makes a larger portion of the image appear sharp. It is also possible to achieve the illusion of deep focus with optical tricks (split-focus diopter) or by compositing two or more images together. The opposite of deep focus is shallow focus, in which the plane of the image that is in focus is very shallow. For example, the foreground might be in focus while the middle-ground and background are out-of-focus. When avoiding deep focus is used specifically for aesthetic effect—especiall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circle Of Confusion
In optics, a circle of confusion (CoC) is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot. In photography, the circle of confusion is used to determine the depth of field, the part of an image that is acceptably sharp. A standard value of CoC is often associated with each image format, but the most appropriate value depends on visual acuity, viewing conditions, and the amount of enlargement. Usages in context include ''maximum permissible circle of confusion'', ''circle of confusion diameter limit'', and the ''circle of confusion criterion''. Real lenses do not focus all rays perfectly, so that even at best focus, a point is imaged as a spot rather than a point. The smallest such spot that a lens can produce is often referred to as the circle of least confusion. Two uses Two important uses of this term and concept n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Derr Hyperfocal 1906 , Ancient Egyptian temple
{{surname, Derr ...
Derr is a surname. Notable people with the surname include: *Allen Derr (1928–2013), American lawyer * A. M. Derr (1903–1970), American politician from Idaho * E.B. Derr (1891 – 1974), American actor * Helen Derr (1918–2011), American journalist * John W. Derr (born 1941), former Maryland State Senator * Kenneth T. Derr, American businessman * Mark Derr, American author * Zac Derr, American football placekicker *Richard Derr (1918–1992), American film and television actor *Jill Mulvay Derr (born 1948), American history professor * Manuela Derr (born 1971), retired East German sprinter See also *Temple of Derr The Temple of Derr or el-Derr is a ''speos'' or rock-cut Egyptian temple, now located in New Amada in Lower Nubia. It was built during the 19th Dynasty by Pharaoh Ramesses II. It is the only rock-cut temple in Nubia, which was constructed by thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-number
In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill Professional, p. 183. It is also known as the focal ratio, f-ratio, or f-stop, and is very important in photography. It is a dimensionless number that is a quantitative measure of lens speed; increasing the f-number is referred to as ''stopping down''. The f-number is commonly indicated using a lower-case hooked f with the format ''N'', where ''N'' is the f-number. The f-number is the reciprocal of the relative aperture (the aperture diameter divided by focal length). Notation The f-number is given by: N = \frac \ where f is the focal length, and D is the diameter of the entrance pupil (''effective aperture''). It is customary to write f-numbers preceded by "", which forms a mathematical expression of the entrance pupil diameter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circle Of Confusion
In optics, a circle of confusion (CoC) is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot. In photography, the circle of confusion is used to determine the depth of field, the part of an image that is acceptably sharp. A standard value of CoC is often associated with each image format, but the most appropriate value depends on visual acuity, viewing conditions, and the amount of enlargement. Usages in context include ''maximum permissible circle of confusion'', ''circle of confusion diameter limit'', and the ''circle of confusion criterion''. Real lenses do not focus all rays perfectly, so that even at best focus, a point is imaged as a spot rather than a point. The smallest such spot that a lens can produce is often referred to as the circle of least confusion. Two uses Two important uses of this term and concept n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infinity Focus
In optics and photography, infinity focus is the state where a lens or other optical system forms an image of an object an infinite distance away. This corresponds to the point of focus for parallel rays. The image is formed at the focal point of the lens. In simple two lens systems such as a refractor telescope, the object at infinity forms an image at the focal point of the objective lens, which is subsequently magnified by the eyepiece. The magnification is equal to the focal length of the objective lens divided by the focal length of the eyepiece. In practice, not all photographic lenses are capable of achieving infinity focus by design. A lens used with an adapter for close-up focusing, for example, may not be able to focus to infinity. Failure of the human eye to achieve infinity focus is diagnosed as myopia. All optics are subject to manufacturing tolerances; even with perfect manufacture, optical trains experience thermal expansion. Focus mechanisms must accommodate p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens (optics)
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices like telescopes, binoculars and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from '' lēns'', the Latin name of the lentil (a seed of a lentil plant), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-stop
In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill Professional, p. 183. It is also known as the focal ratio, f-ratio, or f-stop, and is very important in photography. It is a dimensionless number that is a quantitative measure of lens speed; increasing the f-number is referred to as ''stopping down''. The f-number is commonly indicated using a lower-case hooked f with the format ''N'', where ''N'' is the f-number. The f-number is the reciprocal of the relative aperture (the aperture diameter divided by focal length). Notation The f-number is given by: N = \frac \ where f is the focal length, and D is the diameter of the entrance pupil (''effective aperture''). It is customary to write f-numbers preceded by "", which forms a mathematical expression of the entrance pupil diameter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
