|
Auto-focusing
An autofocus (or AF) optical system uses a sensor, a control system and a motor to focus on an automatically or manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system has to be done manually until indication. Autofocus methods are distinguished as active, passive or hybrid types. Autofocus systems rely on one or more sensors to determine correct focus. Some AF systems rely on a single sensor, while others use an array of sensors. Most modern SLR cameras use through-the-lens optical sensors, with a separate sensor array providing light metering, although the latter can be programmed to prioritize its metering to the same area as one or more of the AF sensors. Through-the-lens optical autofocusing is usually speedier and more precise than manual focus with an ordinary viewfinder, although more precise manual focus can be achieved with special accessories such as focusing magnifiers. Autofocus ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AI Servo
An autofocus (or AF) optical system uses a sensor, a control system and a motor to focus on an automatically or manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system has to be done manually until indication. Autofocus methods are distinguished as active, passive or hybrid types. Autofocus systems rely on one or more sensors to determine correct focus. Some AF systems rely on a single sensor, while others use an array of sensors. Most modern SLR cameras use through-the-lens optical sensors, with a separate sensor array providing light metering, although the latter can be programmed to prioritize its metering to the same area as one or more of the AF sensors. Through-the-lens optical autofocusing is usually speedier and more precise than manual focus with an ordinary viewfinder, although more precise manual focus can be achieved with special accessories such as focusing magnifiers. Autofocus accuracy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for by using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teleconverter
A teleconverter (sometimes called tele extender) is a secondary lens mounted between a camera and a photographic lens which enlarges the central part of an image obtained by the lens. For example, a 2× teleconverter for a 35 mm camera enlarges the central 12×18 mm part of an image to the size of 24×36 mm in the standard 35 mm film format. Teleconverters are typically made in 1.4×, 1.7×, 2× and 3× variants, with 1.4× and 2× being the most common. A 2× teleconverter doubles the apparent focal length of a given lens. Teleconverters also decrease the intensity of the light that reaches the film plane (or sensor) by the square of its magnification. A 2× teleconverter reduces the light to 1/4, doubles the focal ratio and halves the resolution of the master lens it is connected to. This, however, does not necessarily halve the resolution of the digital image. A closely related device reduces the focal length. It is generally marketed under the name speed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canon (company)
is a Japanese multinational corporation headquartered in Ōta, Tokyo, Japan, specializing in optical, imaging, and industrial products, such as lenses, cameras, medical equipment, scanners, printers, and semiconductor manufacturing equipment.Corporate Profile " ''Canon''. Retrieved on 13 January 2009. Canon has a primary listing on the and is a constituent of the Core30 and index. It has a secondary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minolta 7000
The Minolta MAXXUM 7000 (7000 AF in Europe and α-7000 in Japan) 35 mm SLR camera was introduced in February 1985. It was the first camera to feature both integrated autofocus (AF) and motorised film advance, the standard configuration for later amateur and professional single lens reflex cameras. Overview Although the Nikon F3AF (1983), Pentax ME F and Chinon CE-5 already had presented autofocus single lens reflex cameras, autofocusing could not be achieved without the use of special motorised AF lenses. The Pentax ME F had focus sensors in the camera body, while the Chinon CE-5 used a lens with built-in active infrared sensors. Nikon already had a camera with integrated motor drive on the market, the N2000 ( F-301 in UK), but its autofocus counterpart, the N2020 (F-501 in UK), appeared after the Maxxum/Dynax. The Minolta 7000 had its AF sensors and the focusing drive inside the camera body, and as a result the lenses could be much smaller and cheaper. The aperture and focus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nikon F3
The Nikon F3 was Nikon's third professional single-lens reflex camera body, preceded by the F and F2. Introduced in 1980, it had manual and semi-automatic exposure control whereby the camera would select the correct shutter speed (aperture priority automation). The Nikon F3 series cameras had the most model variations of any Nikon F camera. It was also the first of numerous Nikon F-series cameras to be styled by Italian designer Giorgetto Giugiaro, and to include a red stripe on the handgrip – a feature that would later become (with variants of stripes and various other shapes) a signature feature of many Nikon cameras. The F2AS was a current model when the F3 was introduced, and for a while both were sold concurrently. The earlier Nikons had developed such a sterling reputation for extreme ruggedness and durability that many Nikon F and F2 owners were initially reluctant to transition to the new F3 from the F2 series, particularly due to the new camera needing batteries to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
