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Pentax K-mount
The Pentax K-mount, sometimes referred to as the "PK-mount", is a bayonet lens mount standard for mounting interchangeable photographic lenses to 35 mm single-lens reflex (SLR) cameras. It was created by Pentax in 1975, and has since been used by all Pentax 35 mm and digital SLRs and also the MILC Pentax K-01. A number of other manufacturers have also produced many K-mount lenses and K-mount cameras. Mounts The Pentax K-mount has undergone a number of evolutions over the years as new functionality has been added. In general, the term K-mount may refer to the original K-mount, or to all its variations. Originally designed by Zeiss for an alliance with Pentax, it was intended to be a common lens mount for a proposed series of cameras and lenses. However, the plan failed to work out and the two firms parted company amicably, but Pentax retained the lens mount and at least one Zeiss lens design for its own use. K-mount The original K-mount is a simple bayonet con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentax K1000
The Pentax K1000 (originally marked the Asahi Pentax K1000) is an interchangeable lens, 35 mm film, single-lens reflex (SLR) camera, manufactured by Asahi Optical Co., Ltd. from 1976 to 1997, originally in Japan. The K1000's extraordinary longevity makes it a historically significant camera. The K1000's inexpensive simplicity was a great virtue and earned it an unrivaled popularity as a basic but sturdy workhorse. The Pentax K1000 eventually sold over three million units. Description The K1000, introduced in 1976, is the simplest member of Asahi Optical's Pentax K-series 35mm SLRs. The other members are the Pentax K2, KM, and KX, introduced in 1975, and the K2 DMD of 1976. All have the same basic body design, but with differing feature levels, electronics, and controls. The K1000 was the KM with the self-timer, depth of field pre-view and some other features removed to save cost. It uses a horizontal travel, rubberized silk cloth focal plane shutter with a speed range of 1/1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentax ME F
The Pentax ME F was an amateur level, interchangeable lens, 35 mm film, single-lens reflex (SLR) camera. It was manufactured by Asahi Optical Co., Ltd. of Japan from November 1981 to 1984. The ME F was a heavily modified version of the Pentax ME-Super, and a member of the Pentax M-series family of SLRs (see List of Pentax products). It was the first mass-produced SLR camera to come with an autofocus system. Significance and market position The ME F is a historically significant camera. It was the first autofocus (AF) 35 mm SLR camera to reach production. It had a built-in through-the-lens (TTL) electronic contrast detection system to automatically determine proper subject focus and drive a lens to that focus point. Although it autofocused poorly and was a commercial failure, the pioneering ME F was a major milestone in the history of camera technology that pointed the way to all present day AF SLRs. Most new cameras today, whether film, video or digital, have some sort of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DC Motor
A DC motor is any of a class of rotary electrical motors that converts direct current (DC) electrical energy into mechanical energy. The most common types rely on the forces produced by induced magnetic fields due to flowing current in the coil. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current in part of the motor. DC motors were the first form of motors widely used, as they could be powered from existing direct-current lighting power distribution systems. A DC motor's speed can be controlled over a wide range, using either a variable supply voltage or by changing the strength of current in its field windings. Small DC motors are used in tools, toys, and appliances. The universal motor, a lightweight brushed motor used for portable power tools and appliances can operate on direct current and alternating current. Larger DC motors are currently used in propulsion of electric vehicle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrasonic Motor
An ultrasonic motor is a type of piezoelectric motor powered by the ultrasonic vibration of a component, the stator, placed against another component, the rotor or slider depending on the scheme of operation (rotation or linear translation). Ultrasonic motors differ from other piezoelectric motors in several ways, though both typically use some form of piezoelectric material, most often lead zirconate titanate and occasionally lithium niobate or other single-crystal materials. The most obvious difference is the use of resonance to amplify the vibration of the stator in contact with the rotor in ultrasonic motors. Ultrasonic motors also offer arbitrarily large rotation or sliding distances, while piezoelectric actuators are limited by the static strain that may be induced in the piezoelectric element. One common application of ultrasonic motors is in camera lenses where they are used to move lens elements as part of the auto-focus system. Ultrasonic motors replace the noisier and ofte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentax K10D
The Pentax K10D and similar Samsung GX-10 are 10.2-megapixel digital single-lens reflex cameras launched in late 2006. They were developed in a collaboration between Pentax of Japan and Samsung of South Korea. The K10D was announced on 13 September 2006, and released in mid-November 2006, while Samsung announced the GX-10 on 2006-09-21 and it became available on January 1, 2007. The Pentax K20D, successor to the K10D, was officially announced on January 23, 2008. The K10D has been hailed by ''Popular Photography and Imaging'' magazine as "an all-star player," and was named as a finalist for their 2007 "Camera of the Year" award. Technology and construction It combines a 10.2 effective megapixel CCD sensor, coupled with a 22-bit analog-to-digital converter (ADC) and a shake reduction system which also provides a dust removal feature to keep dust off the sensor surface. The K10D features a new image processor called ''PRIME'' (Pentax Real IMage Engine), which interfaces with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Transfer Function
The optical transfer function (OTF) of an optical system such as a camera, microscope, human eye, or projector specifies how different spatial frequencies are captured or transmitted. It is used by optical engineers to describe how the optics project light from the object or scene onto a photographic film, detector array, retina, screen, or simply the next item in the optical transmission chain. A variant, the modulation transfer function (MTF), neglects phase effects, but is equivalent to the OTF in many situations. Either transfer function specifies the response to a periodic sine-wave pattern passing through the lens system, as a function of its spatial frequency or period, and its orientation. Formally, the OTF is defined as the Fourier transform of the point spread function (PSF, that is, the impulse response of the optics, the image of a point source). As a Fourier transform, the OTF is complex-valued; but it will be real-valued in the common case of a PSF that is symmet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KAF2-2
KAF, Kaf or Kafs may refer to: Places * Mount Qaf or Kaf, a mythical place in medieval Islamic cosmology * Kaf, a city in Al Jawf Province, Saudi Arabia * Kandahar International Airport or Kandahar Air Field (KAF), near Kandahar, Afghanistan Organisations * Communist Workers League (Sweden) ( sv, Kommunistiska Arbetarförbundet), a Swedish Trotskyist political party now called the Socialist Party * Kalki Avatar Foundation, a spiritualist organisation based in London, UK * Korean Alpine Federation, a member of the International Ski Mountaineering Federation * Kyrgyz Air (ICAO code), a privately owned airline based in Kyrgyzstan * Karato Airport (IATA code), Papua New Guinea; See List of airports by IATA code: K * Korean Anarchist Federation, see Anarchism in Korea Military * Kenya Air Force, the national Air Force of Kenya * Khmer National Air Force, the air force branch of the Khmer National Armed Forces, the official military of the Khmer Republic during the Cambodian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aperture Priority
Aperture priority, often abbreviated ''A'' or ''Av'' (for aperture value) on a camera mode dial, is a mode on some cameras that allows the user to set a specific aperture value (f-number) while the camera selects a shutter speed to match it that will result in proper exposure based on the lighting conditions as measured by the camera's light meter. This is different from manual mode, where the user must decide both values, shutter priority where the user picks a shutter speed with the camera selecting an appropriate aperture, or program mode where the camera selects both. Uses Depth of field As an image's depth of field is inversely proportional to the size of the lens's aperture, aperture priority mode is often used to allow the photographer to control the focus of objects in the frame. Aperture priority is therefore useful in landscape photography, for example, where it may be desired that objects in foreground, middle distance, and background all be rendered crisply, while shut ... [...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 in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure (photography)
In photography, exposure is the amount of light per unit area (the image plane's illuminance times the exposure time) reaching a frame of photographic film or the surface of an electronic image sensor, as determined by shutter speed, lens F-number, and scene luminance. Exposure is measured in lux seconds, and can be computed from exposure value (EV) and scene luminance in a specified region. An "exposure" is a single shutter cycle. For example, a long exposure refers to a single, long shutter cycle to gather enough dim light, whereas a multiple exposure involves a series of shutter cycles, effectively layering a series of photographs in one image. The accumulated ''photometric exposure'' (''H''v) is the same so long as the total exposure time is the same. Definitions Radiant exposure Radiant exposure of a ''surface'', denoted ''H''e ("e" for "energetic", to avoid confusion with photometric quantities) and measured in , is given by :H_\mathrm = E_\mathrmt, where *''E'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shutter Priority
Shutter priority (usually denoted as S on the mode dial), also called time value (abbreviated as Tv), refers to a setting on cameras that allows the user to choose a specific shutter speed while the camera adjusts the aperture to ensure correct exposure. This is different from manual mode, where the user must decide both values, aperture priority where the user picks an aperture with the camera selecting the shutter speed to match, or program mode where the camera selects both. Background Shutter priority with longer exposures is chosen to create an impression of motion. For example, a waterfall will appear blurred and fuzzy. If the camera is panned with a moving subject, the background will appear blurred. When photographing sports or high-speed phenomena, shutter priority with short exposures can ensure that the motion is effectively ''frozen'' in the resulting image. Like aperture priority, this mode allows for partial automation thus decreasing the need for total concentrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentax A 50mm F1
is a brand name used primarily by the Japanese multinational imaging and electronics company Ricoh for DSLR cameras, lenses, sport optics (including binoculars and rifle scopes), and CCTV optics. The Pentax brand is also used by Hoya Corporation for medical products & services, TI Asahi for surveying instruments, and Seiko Optical Products for certain optical lenses. Corporate history Early history The company was founded as Asahi Kogaku Goshi Kaisha in November 1919 by Kumao Kajiwara, at a shop in the Toshima suburb of Tokyo, and began producing spectacle lenses (which it still manufactures). In 1938 it changed its name to , and by this time it was also manufacturing camera/cine lenses. In the lead-up to World War II, Asahi Optical devoted much of its time to fulfilling military contracts for optical instruments. At the end of the war, Asahi Optical was disbanded by the occupying powers, being allowed to re-form in 1948. The company resumed its pre-war activities, manufacturi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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