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Metal Oxide Semiconductor
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. A metal-insulator-semiconductor field-effect transistor (MISFET) is a term almost synonymous with MOSFET. Another synonym is IGFET for insulated-gate field-effect transistor. The basic principle of the field-effect transistor was first patented by Julius Edgar Lilienfeld in 1925.Lilienfeld, Julius Edgar (1926-10-08) "Method and apparatus for controlling electric currents" upright=1.6, Two power MOSFETs in V_in_the_''off''_state,_and_can_conduct_a_con­ti­nuous_current_of_30  surface-mount_packages._Operating_as_switches,_each_of_these_components_can ...
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Active Pixel Sensor
An active-pixel sensor (APS) is an image sensor where each pixel sensor unit cell has a photodetector (typically a pinned photodiode) and one or more active transistors. In a metal–oxide–semiconductor (MOS) active-pixel sensor, MOS field-effect transistors (MOSFETs) are used as amplifiers. There are different types of APS, including the early NMOS APS and the now much more common complementary MOS (CMOS) APS, also known as the CMOS sensor. CMOS sensors are used in digital camera technologies such as cell phone cameras, web cameras, most modern digital pocket cameras, most digital single-lens reflex cameras (DSLRs), and mirrorless interchangeable-lens cameras (MILCs). CMOS sensors emerged as an alternative to charge-coupled device (CCD) image sensors and eventually outsold them by the mid-2000s decade. The term ''active pixel sensor'' is also used to refer to the individual pixel sensor itself, as opposed to the image sensor. In this case, the image sensor is sometimes call ...
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Four Thirds System
The Four Thirds System is a standard created by Olympus and Eastman Kodak for digital single-lens reflex camera (DSLR) and mirrorless camera design and development. The system provides a standard that, with digital cameras and lenses available from multiple manufacturers, allows for the interchange of lenses and bodies from different manufacturers. seems to cover the standard. Proponents describe it as an open standard, but companies may use it only under a non-disclosure agreement. Unlike older single-lens reflex (SLR) systems, Four Thirds was designed from the start to be entirely digital. Many lenses are extensively computerised, to the point that Olympus offers firmware updates for many of them. Lens design has been tailored to the requirements of digital sensors, most notably through telecentric designs. The size of the sensor is significantly smaller than for most DSLRs and this implies that lenses, especially telephoto lenses, can be smaller. For example, a Four Thir ...
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APS-C
Advanced Photo System type-C (APS-C) is an image sensor format approximately equivalent in size to the Advanced Photo System film negative in its C ("Classic") format, of 25.1×16.7 mm, an aspect ratio of 3:2 and Ø 31.15 mm field diameter. It is therefore also equivalent in size to the Super 35 motion picture film format, which has the dimensions of 24.89 mm × 18.66 mm (0.980 in × 0.735 in) and Ø 31.11 mm field diameter. Sensors approximating these dimensions are used in many digital single-lens reflex cameras (DSLRs), mirrorless interchangeable-lens cameras (MILCs), and a few large-sensor live-preview digital cameras. APS-C size sensors are also used in a few digital rangefinders. Such sensors exist in many different variants depending on the manufacturer and camera model. All APS-C variants are considerably smaller than 35 mm standard film which measures 36×24 mm. Because of this, devices with APS-C sensors are known as "cro ...
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Image Sensor Format
In digital photography, the image sensor format is the shape and size of the image sensor. The image sensor format of a digital camera determines the angle of view of a particular lens when used with a particular sensor. Because the image sensors in many digital cameras are smaller than the 24 mm × 36 mm image area of full-frame 35 mm cameras, a lens of a given focal length gives a narrower field of view in such cameras. Sensor size is often expressed as optical format in inches. Other measures are also used; see table of sensor formats and sizes below. Lenses produced for 35 mm film cameras may mount well on the digital bodies, but the larger image circle of the 35 mm system lens allows unwanted light into the camera body, and the smaller size of the image sensor compared to 35 mm film format results in cropping of the image. This latter effect is known as field-of-view crop. The format size ratio (relative to the 35 mm film format) is ...
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Olympus E-500
The Olympus E-500 (Olympus EVOLT E-500 in North America) is an 8-megapixel digital SLR camera manufactured by Olympus of Japan and based on the Four Thirds System. It was announced on 26 September 2005. Like the E-300 launched the previous year, it uses a Full Frame Transfer (17.3 x 13 mm) Kodak KAF-8300CE CCD imaging chip. Features Unlike the E-300 and the E-300's successor, the Olympus E-330, the E-500 retains the traditional SLR appearance, with a humped pentamirror box instead of the E-300's unique Porro mirror arrangement. The mirror box also bears the onboard flash. The viewfinder hump means the E-500 is taller than the E-300, but in other dimensions it is smaller. The E-500 uses Olympus' patented Supersonic Wave Filter dust reduction system to shake dust from the sensor during startup and when requested by the user; this largely eliminates the problem of dust accumulation on the surface of the image sensor. Image processing is done with Olympus' TruePic Turbo system. ...
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Olympus E-400
The Olympus E-400 is a digital single-lens reflex camera launched by Olympus on 14 September 2006, using the Four Thirds System lens mount standard. This 10 megapixel camera could be compared to other DSLRs unveiled during the summer of 2006 with comparable pixel count and price range: the Sony α 100, the Nikon D80, the Canon EOS 400D and the Pentax K10D. Features The E-400 is notable for its small size, omitting the hand grip and exploiting the smaller sensor. It weighs only 375g and approaches manual focus film SLRs sizes, reminiscent of the Olympus OM system. It was accompanied by two new small zoom lenses, a 14–42 mm (28–84 mm 135 film format equivalent) f/3.5–5.6 standard zoom weighing 190g and a 40–150 mm (80–300 mm equivalent) f/4.0–5.6 long zoom weighing 220g. The body and single lens kit have a 700GB£ MSRP and 850GB£ for the two lens kit. The E-400, like all of the Olympus E-system cameras, uses Olympus' patented Supersonic Wave Fil ...
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Olympus E-300
The Olympus E-300 (Olympus Evolt E-300 in North America) is an 8-megapixel digital SLR manufactured by Olympus of Japan and based on the Four Thirds System. Announced at photokina 2004, it became available at the end of 2004. It was the second camera (after the Olympus E-1) to use the Four Thirds System, and the first intended for the consumer mark Features The camera's appearance was unique, as it lacked the ubiquitous SLR pentaprism "hump". Instead, a Porro prism system was used; it fitted sideways within the camera, with a sideways-swinging mirror, and located the viewfinder eyepiece to the left (seen from behind) relative to the lens centerline. The body was largely of ABS plastic over a metal frame; the lens mount was metal, and there was a metal covered area on the left top of the camera. This area also contained the onboard flash, which popped up and forward at the touch of a button. The onboard flash popup mechanism is manual. In low light scenarios the flash will not ...
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Olympus E-1
The Olympus E-1, introduced in 2003, was the first DSLR system camera designed from the ground up for digital photography This contrasts with its contemporaries which offered systems based on reused parts from previous 135 film systems, modified to fit with a sensor size of APS-C. Features The E-1 uses the Four Thirds System lens mount and imaging system. This design choice means that because the CCD is smaller than a 35 mm negative, Four Thirds System lenses and camera bodies can be made smaller and lighter than those of preceding SLRs. Characteristics: *Lighter/more compact than contemporary DSLR bodies *5 megapixel CCD *Good dynamic range and exposure *Magnesium-alloy body *Environmental sealing (splash proof) *"Supersonic Wave Filter" dust reduction system cleans CCD at each camera start-up (dust is shaken off the CCD) * USB 2.0 and FireWire connectivity *Continuous shooting 3 frames per second up to 12 frames *Hybrid white balance sensor (on external surface of camer ...
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Image Noise
Image noise is random variation of brightness or color information in images, and is usually an aspect of electronic noise. It can be produced by the image sensor and circuitry of a scanner or digital camera. Image noise can also originate in film grain and in the unavoidable shot noise of an ideal photon detector. Image noise is an undesirable by-product of image capture that obscures the desired information. Typically the term “image noise” is used to refer to noise in 2D images, not 3D images. The original meaning of "noise" was "unwanted signal"; unwanted electrical fluctuations in signals received by AM radios caused audible acoustic noise ("static"). By analogy, unwanted electrical fluctuations are also called "noise". Image noise can range from almost imperceptible specks on a digital photograph taken in good light, to optical and radioastronomical images that are almost entirely noise, from which a small amount of information can be derived by sophisticated pr ...
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Live Preview
Live preview is a feature that allows a digital camera's display screen to be used as a viewfinder. This provides a means of previewing framing and other exposure before taking the photograph. In most such cameras, the preview is generated by means of continuously and directly projecting the image formed by the lens onto the main image sensor. This in turn feeds the electronic screen with the live preview image. The electronic screen can be either a liquid crystal display (LCD) or an electronic viewfinder (EVF). Background The concept for cameras with live preview largely derives from electronic (video) TV cameras. Until 1995 most digital cameras did not have live preview, and it was more than ten years after this that the higher end digital single-lens reflex cameras (DSLR) adopted this feature, as it is fundamentally incompatible with the swinging-mirror single-lens reflex mechanism. The first digital still camera with an LCD for autogain framing live preview was the ...
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Charge-coupled Device
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging. In a CCD image sensor, pixels are represented by p-doped metal–oxide–semiconductor (MOS) capacitors. These MOS capacitors, the basic building blocks of a CCD, are biased above the threshold for inversion when image acquisition begins, allowing the conversion of incoming photons into electron charges at the semiconductor-oxide interface; the CCD is then used to read out these charges. Although CCDs are not the only technology to allow for light detection, CCD image sensors are widely used in professional, medical, and scientific applications where high-quality image data are required. In applications with less exacting quality demands, such as consumer and professional digital cameras, a ...
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