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Canon EF 300mm Lens
The EF 300mm lens refers to a family of telephoto prime lenses made by Canon, five of which have been sold to the general public and one of which was only made on special order. The lenses have an EF type mount which fits the Canon EOS line of cameras. When used on a digital EOS body with a field of view compensation factor of 1.3x, such as the Canon EOS-1D Mark IV, it provides a narrow field of view, equivalent to a 390 mm lens mounted on a 35mm frame body. With a 1.6x body such as the Canon EOS 650D, it provides a narrower field of view, equivalent to a 480 mm lens mounted on a 35mm frame body. This lens is most commonly used by sports and wildlife photographers, but is short enough to be use for extreme close-up portraits. Because of its rather high native magnification, it can be used for some macro type photography. Technical information The EF 300mm is a L series lens. This lens is constructed with a metal body and mount, and with plastic extremities and switch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephoto
A telephoto lens, in photography and cinematography, is a specific type of a long-focus lens 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. Telephoto lenses are sometimes broken into the further sub-types of short telephoto (85–135 mm in 35 mm film format), medium telephoto: (135–300 mm in 35 mm film format) and super telephoto (over 300 mm in 35 mm film format) . Construction In contrast to a telephoto lens, for any given focal leng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dispersion (optics)
In optics, and by analogy other branches of physics dealing with wave propagation, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency; sometimes the term chromatic dispersion is used for specificity to optics in particular. A medium having this common property may be termed a dispersive medium (plural ''dispersive media''). Although the term is used in the field of optics to describe light and other electromagnetic waves, dispersion in the same sense can apply to any sort of wave motion such as acoustic dispersion in the case of sound and seismic waves, and in gravity waves (ocean waves). Within optics, dispersion is a property of telecommunication signals along transmission lines (such as microwaves in coaxial cable) or the pulses of light in optical fiber. Physically, dispersion translates in a loss of kinetic energy through absorption. In optics, one important and familiar consequence of dispersion is the change in the angle of refra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 optical system typically has many openings or structures that limit the ray bundles (ray bundles are also known as ''pencils'' of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that primarily determines the ray cone angle and brightness at the image point. In some contexts, especially in photography and astronomy, ''aperture'' refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope, the apertur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macro Photography
Macro photography (or photomacrography or macrography, and sometimes macrophotography) is extreme close-up photography, usually of very small subjects and living organisms like insects, in which the size of the subject in the photograph is greater than life size (though ''macrophotography'' also refers to the art of making very large photographs). By the original definition, a macro photograph is one in which the size of the subject on the negative or image sensor is life size or greater. In some senses, however, it refers to a finished photograph of a subject that is greater than life size. The ratio of the subject size on the film plane (or sensor plane) to the actual subject size is known as the reproduction ratio. Likewise, a macro lens is classically a lens capable of reproduction ratios of at least 1:1, although it often refers to any lens with a large reproduction ratio, despite rarely exceeding 1:1. Apart from technical photography and film-based processes, where the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X Mark
An X mark (also known as an ex mark or a cross mark or simply an X or ex or a cross) is used to indicate the concept of negation (for example "no, this has not been verified", "no, that is not the correct answer" or "no, I do not agree") as well as an indicator (for example, in election ballot papers or in maps as an x-marks-the-spot). Its opposite is often considered to be the check mark or tick (or the O mark used in Japan and Korea). In Japanese, the X mark (❌) is called "batsu" (ばつ) and can be expressed by someone by crossing their arms. It is also used as a replacement for a signature for a person who is blind or illiterate and thus cannot write their name. Typically, the writing of an X used for this purpose must be witnessed to be valid. As a verb, to X (or ex) off/out or to cross off/out means to add such a mark. It is quite common, especially on printed forms and document, for there to be squares in which to place x marks, or interchangeably checks. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yes Check
Yes or YES may refer to: * An affirmative particle in the English language; see yes and no Education * YES Prep Public Schools, Houston, Texas, US * YES (Your Extraordinary Saturday), a learning program from the Minnesota Institute for Talented Youth * Young Eisner Scholars, in Los Angeles, New York City, Chicago, and Appalachia, US * Young Epidemiology Scholars, US Technology * yes (Unix), command to output "y" or a string repeatedly * Philips :YES, a 1985 home computer * Yes! Roadster, a German sports car Transportation * Yasuj Airport, Iran, IATA airport code * YES Airways, later OLT Express, Poland Organization * Yale Entrepreneurial Society, US * YES Snowboards * The YES! Association, a Swedish artist collective * Yes! Youth Movement, Russia * Young European Socialists formally ECOSY * Youth Empowerment Scheme, a children's charity, Belfast, Northern Ireland * Youth Energy Squad (Y.E.S) * YES (Lithuanian political party) Literature * ''Yes!'' (Hong Kong magazine) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Full-frame Digital SLR
A full-frame DSLR is a digital single-lens reflex camera (DSLR) with a 35 mm image sensor format (). Historically, 35 mm was one of the standard film formats, alongside larger ones, such as medium format and large format. The full-frame DSLR is in contrast to full-frame mirrorless interchangeable-lens cameras, and DSLR and mirrorless cameras with smaller sensors (for instance, those with a size equivalent to APS-C-size film), much smaller than a full 35 mm frame. Many digital cameras, both compact and SLR models, use a smaller-than-35 mm frame as it is easier and cheaper to manufacture imaging sensors at a smaller size. Historically, the earliest digital SLR models, such as the Nikon NASA F4 or Kodak DCS 100, also used a smaller sensor. Kodak states that 35 mm film (note: in " Academy format", 21.0 mm × 15.2 mm) has the equivalent of 6K horizontal resolution, according to a senior vice president of IMAX. This equates to 10K horizontal resolution in f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canon EF 300mm F4L IS USM 3945
Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the conceptual material accepted as official in a fictional universe by its fan base * Literary canon, an accepted body of works considered as high culture ** Western canon, the body of high culture literature, music, philosophy, and works of art that is highly valued in the West * Canon of proportions, a formally codified set of criteria deemed mandatory for a particular artistic style of figurative art * Canon (music), a type of composition * Canon (hymnography), a type of hymn used in Eastern Orthodox Christianity. * ''Canon'' (album), a 2007 album by Ani DiFranco * ''Canon'' (film), a 1964 Canadian animated short * ''Canon'' (game), an online browser-based strategy war game * ''Canon'' (manga), by Nikki * Canonical plays of William Shakespeare * ''The Canon'' (Natalie Angier book), a 2007 science book by Natalie Angier * ''The Canon'' (podcast), concerning film Brands and enterprises * Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
