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Pincushion Distortion
In geometric optics, distortion is a deviation from rectilinear projection; a projection in which straight lines in a scene remain straight in an image. It is a form of optical aberration that may be distinguished from other aberrations such as spherical aberration, coma, chromatic aberration, field curvature, and astigmatism in a sense that these impact the image sharpness without changing an object shape or structure in the image (e.g., a straight line in an object is still a straight line in the image although the image sharpness may be degraded by the mentioned aberrations) while distortion can change the object structure in the image (so named as distortion). Radial distortion Although distortion can be irregular or follow many patterns, the most commonly encountered distortions are radially symmetric, or approximately so, arising from the symmetry of a photographic lens. These ''radial distortions'' can usually be classified as either ''barrel'' distortions or ''pincus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spherical Aberration
In optics, spherical aberration (SA) is a type of aberration found in optical systems that have elements with spherical surfaces. This phenomenon commonly affects lenses and curved mirrors, as these components are often shaped in a spherical manner for ease of manufacturing. Light rays that strike a spherical surface off-centre are refracted or reflected more or less than those that strike close to the centre. This deviation reduces the quality of images produced by optical systems. The effect of spherical aberration was first identified in the 11th century by Ibn al-Haytham who discussed it in his work Kitāb al-Manāẓir. Overview A spherical lens has an aplanatic point (i.e., no spherical aberration) only at a lateral distance from the optical axis that equals the radius of the spherical surface divided by the index of refraction of the lens material. Spherical aberration makes the focus of telescopes and other instruments less than ideal. This is an important effect, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadratic Function
In mathematics, a quadratic function of a single variable (mathematics), variable is a function (mathematics), function of the form :f(x)=ax^2+bx+c,\quad a \ne 0, where is its variable, and , , and are coefficients. The mathematical expression, expression , especially when treated as an mathematical object, object in itself rather than as a function, is a quadratic polynomial, a polynomial of degree two. In elementary mathematics a polynomial and its associated polynomial function are rarely distinguished and the terms ''quadratic function'' and ''quadratic polynomial'' are nearly synonymous and often abbreviated as ''quadratic''. The graph of a function, graph of a function of a real variable, real single-variable quadratic function is a parabola. If a quadratic function is equation, equated with zero, then the result is a quadratic equation. The solutions of a quadratic equation are the zero of a function, zeros (or ''roots'') of the corresponding quadratic function, of which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Chromatic Aberration
In optics, chromatic aberration (CA), also called chromatic distortion, color aberration, color fringing, or purple fringing, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the lens elements varies with the wavelength of light. The refractive index of most transparent materials decreases with increasing wavelength. Since the focal length of a lens depends on the refractive index, this variation in refractive index affects focusing. Since the focal length of the lens varies with the color of the light different colors of light are brought to focus at different distances from the lens or with different levels of magnification. Chromatic aberration manifests itself as "fringes" of color along boundaries that separate dark and bright parts of the image. Types There are two types of chromatic aberration: ''axial'' (''longitudinal''), and ''transverse'' (''lateral''). Axial aberration occurs when different wavelength ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concentric
In geometry, two or more objects are said to be ''concentric'' when they share the same center. Any pair of (possibly unalike) objects with well-defined centers can be concentric, including circles, spheres, regular polygons, regular polyhedra, parallelograms, cones, conic sections, and quadrics. Geometric objects are '' coaxial'' if they share the same axis (line of symmetry). Geometric objects with a well-defined axis include circles (any line through the center), spheres, cylinders, conic sections, and surfaces of revolution. Concentric objects are often part of the broad category of '' whorled patterns'', which also includes '' spirals'' (a curve which emanates from a point, moving farther away as it revolves around the point). Geometric properties In the Euclidean plane, two circles that are concentric necessarily have different radii from each other.. However, circles in three-dimensional space may be concentric, and have the same radius as each other, but nevert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Didactic
Didacticism is a philosophy that emphasises instructional and informative qualities in literature, art, and design. In art, design, architecture, and landscape, didacticism is a conceptual approach that is driven by the urgent need to explain. Overview The term has its origin in the Ancient Greek word διδακτικός (''didaktikos''), "pertaining to instruction", and signified learning in a fascinating and intriguing manner. Didactic art was meant both to entertain and to instruct. Didactic plays, for instance, were intended to convey a moral theme or other rich truth to the audience. During the Middle Age, the Roman Catholic chants like the '' Veni Creator Spiritus'', as well as the Eucharistic hymns like the '' Adoro te devote'' and '' Pange lingua'' are used for fixing within prayers the truths of the Roman Catholic faith to preserve them and pass down from a generation to another. In the Renaissance, the church began a syncretism between pagan and the Christian didacti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotational Symmetry
Rotational symmetry, also known as radial symmetry in geometry, is the property a shape (geometry), shape has when it looks the same after some rotation (mathematics), rotation by a partial turn (angle), turn. An object's degree of rotational symmetry is the number of distinct Orientation (geometry), orientations in which it looks exactly the same for each rotation. Certain geometric objects are partially symmetrical when rotated at certain angles such as squares rotated 90°, however the only geometric objects that are fully rotationally symmetric at any angle are spheres, circles and other spheroids. Formal treatment Formally the rotational symmetry is symmetry with respect to some or all rotations in -dimensional Euclidean space. Rotations are Euclidean group#Direct and indirect isometries, direct isometries, i.e., Isometry, isometries preserving Orientation (mathematics), orientation. Therefore, a symmetry group of rotational symmetry is a subgroup of (see Euclidean g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WA 80 Cm Archery Target
Wa or WA may refer to: Businesses and organizations * KLM Cityhopper (IATA airline designator WA) * Weerbaarheidsafdeling, a paramilitary force associated with the Dutch National Socialist Movement * Western Airlines (IATA airline designator WA) (defunct) * Western Arms, a Japan-based airsoft manufacturer * Western Assurance Company, operating as WA, a Canadian insurance company * World Aquatics, the international governing body of water sports * World Archery, the international governing body of the sport of archery * World Athletics, the international governing body for the sport of athletics Language * Wa (Javanese) (ꦮ), a letter in the Javanese script * Wa (kana), romanisation of the Japanese kana わ and ワ * Wa language, a group of languages spoken by the Wa people * Walloon language (ISO 639 language code ''wa'') Places Asia * Wa (Japan) (和), an old Chinese name for Japan * Wa Land, the natural and historical region inhabited mainly by the Wa peopl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binoculars
Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held using both hands, although sizes vary widely from opera glasses to large pedestal-mounted military models. Unlike a (monocular) telescope, binoculars give users a stereopsis, three-dimensional image: each eyepiece presents a slightly different image to each of the viewer's eyes and the parallax allows the visual cortex to generate an depth perception, impression of depth. Optical design evolution Galilean 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. Most early binoculars used Galilean telescope, Galilean optics; that is, they used a convex lens, convex objective (optics), objective and a concave lens, concave eyepi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nikon
(, ; ) is a Japanese optics and photographic equipment manufacturer. Nikon's products include cameras, camera lenses, binoculars, microscopes, ophthalmic lenses, measurement instruments, rifle scopes, spotting scopes, and equipment related to Semiconductor device fabrication, semiconductor fabrication, such as Stepper, steppers used in the photolithography steps of such manufacturing. Nikon is the world's second largest manufacturer of such equipment. Since July 2024, Nikon has been headquartered in Nishi-Ōi, Shinagawa, Shinagawa, Tokyo where the plant has been located since 1918. The company is the eighth-largest chip equipment maker as reported in 2017. Also, it has diversified into new areas like 3D printers, 3D printing and regenerative medicine to compensate for the shrinking digital camera market. Among Nikon's many notable product lines are Nikkor imaging lenses (for Nikon F-mount, F-mount cameras, large format photography, photographic enlargers, and other applicatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephoto Lens
A telephoto lens, also known as telelens, is a specific type of a long-focus lens used in photography and cinematography, in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a ''telephoto group'' that extends the light path to create a long-focus lens in a much shorter overall design. The angle of view and other effects of long-focus lenses are the same for telephoto lenses of the same specified focal length. Long-focal-length lenses are often informally referred to as ''telephoto lenses'', although this is technically incorrect: a telephoto lens specifically incorporates the telephoto group. Construction A simple photographic lens may be constructed using one lens element of a given focal length; to focus on an object at infinity, the distance from this single lens to focal plane of the camera (where the sensor or film is) has to be adjusted to the focal length of that lens. For example, g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canon EF 50mm Lens
The EF 50mm lenses are a group of normal lens, normal prime lens, prime photographic lens, lenses made by Canon (company), Canon that share the same focal length. These lenses are based on the classic double-Gauss lens, with the f/1.8 being a standard six-element double-Gauss with an air gap and powers between element 2 and 3 and its Lens speed, faster cousins adding additional elements. The 50mm focal length, when used with a 35mm film or full-frame sensor, has been widely considered to match the perspective seen by the human eye. Canon 50mm lenses have an Canon EF lens mount, EF type mount that fits the Canon EOS line of cameras. When pairing a 50mm lens to a Canon DSLR with an APS-C sized sensor, the crop factor effectively turns the 50mm focal length into an 80mm field of view. Seven EF 50mm lenses have been sold by Canon: * 1.0L USM (discontinued, replaced by 1.2L USM) * 1.2L USM * 1.4 USM * 1.8 (discontinued, replaced by 1.8 II) * 1.8 II (discontinued, replaced by 1.8 STM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
