1.
Digital single-lens reflex camera
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A digital single-lens reflex camera is a digital camera that combines the optics and the mechanisms of a single-lens reflex camera with a digital imaging sensor, as opposed to photographic film. The reflex design scheme is the difference between a DSLR and other digital cameras. In the reflex design, light travels through the lens, then to a mirror that alternates to send the image to either the viewfinder or the image sensor, the alternative would be to have a viewfinder with its own lens, hence the term single lens for this design. By using only one lens, the viewfinder of a DSLR presents an image that will not perceptibly differ from what is captured by the cameras sensor, like SLRs DSLRs typically use interchangeable lenses with a proprietary lens mount. A movable mechanical mirror system is switched down to light from the lens over a matte focusing screen via a condenser lens. Most of the entry-level DSLRs use a instead of the traditional pentaprism. Focusing can be manual or automatic, activated by pressing half-way on the release or a dedicated AF button. DSLRs typically use autofocus based on phase detection and this method allows the optimal lens position to be calculated, rather than found, as would be the case with autofocus based on contrast maximisation. Phase-detection autofocus is typically faster than other passive techniques, as the phase sensor requires the same light going to the image sensor, it was previously only possible with an SLR design. Digital SLR cameras, along with most other cameras, generally have a mode dial to access standard camera settings or automatic scene-mode settings. Sometimes called a PASM dial, they typically provide such as program, aperture-priority, shutter-priority. Scene modes vary from camera to camera, and these modes are inherently less customizable and they often include landscape, portrait, action, macro, night, and silhouette, among others. However, these different settings and shooting styles that scene mode provides can be achieved by calibrating certain settings on the camera, professional DSLRs seldom contain automatic scene modes as professionals often do not require these and professionals know how to achieve the looks they want. A method to prevent dust entering the chamber, by using a dust cover filter right behind the mount, was used by Sigma in its first DSLR. Olympus used a built-in sensor cleaning mechanism in its first DSLR that had a sensor exposed to air, several Canon DSLR cameras rely on dust reduction systems based on vibrating the sensor at ultrasonic frequencies to remove dust from the sensor. Interchangeable lenses for SLRs and DSLRs are built to operate correctly with a lens mount that is generally unique to each brand. There are also lens adapters that allow a lens for one mount to be used on a camera body with a different lens mount. Many lenses are mountable, diaphragm-and-meter-compatible, on modern DSLRs and on older film SLRs that use the lens mount
2.
Camera lens
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A lens might be permanently fixed to a camera, or it might be interchangeable with lenses of different focal lengths, apertures, and other properties. While in principle a simple convex lens will suffice, in practice a compound made up of a number of optical lens elements is required to correct the many optical aberrations that arise. Some aberrations will be present in any lens system and it is the job of the lens designer to balance these and produce a design that is suitable for photographic use and possibly mass production. Typical rectilinear lenses can be thought of as improved pinhole lenses, as shown, a pinhole lens is simply a small aperture that blocks most rays of light, ideally selecting one ray to the object for each point on the image sensor. Here a pixel is the area of the detector exposed to light from a point on the object, making the pinhole smaller improves resolution, but reduces the amount of light captured. At a certain point, shrinking the hole does not improve the resolution because of the diffraction limit, beyond this limit, making the hole smaller makes the image blurrier as well as darker. Practical lenses can be thought of as an answer to the question how can a pinhole lens be modified to more light. A first step is to put a simple convex lens at the pinhole with a length equal to the distance to the film plane. The geometry is almost the same as with a pinhole lens. From the front of the camera, the hole, would be seen. If one were inside the camera, one would see the acting as a projector. The virtual image of the aperture from inside the camera is the exit pupil. Practical photographic lenses include more lens elements, a camera lens may be made from a number of elements, from one, as in the Box Brownies meniscus lens, to over 20 in the more complex zooms. These elements may themselves comprise a group of lenses cemented together, the front element is critical to the performance of the whole assembly. In all modern lenses the surface is coated to reduce abrasion, flare, and surface reflectance, to minimize aberration, the curvature is usually set so that the angle of incidence and the angle of refraction are equal. In a prime lens this is easy, but in a zoom there is always a compromise, the lens usually is focused by adjusting the distance from the lens assembly to the image plane, or by moving elements of the lens assembly. To improve performance, some lenses have a cam system that adjusts the distance between the groups as the lens is focused, manufacturers call this different things, Nikon calls it CRC, Canon calls it a floating system, and Hasselblad and Mamiya call it FLE. Glass is the most common used to construct lens elements, due to its good optical properties
3.
Canon EF lens mount
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Introduced in 1987, the EF lens mount is the standard lens mount on the Canon EOS family of SLR film and digital cameras. EF stands for Electro-Focus, automatic focusing on EF lenses is handled by an electric motor built into the lens. Mechanically, it is a mount, and all communication between camera and lens takes place through electrical contacts, there are no mechanical levers or plungers. In 2003, Canon introduced the EF-S lens mount, a derivative of the EF mount that is strictly for digital EOS cameras with APS-C sensors released after 2003, EF lenses can be mounted on EF-S bodies but EF-S lenses cannot be mounted on EF bodies. In October 2012, Canon introduced the EF-M lens mount, a derivative designed exclusively for mirrorless cameras with APS-C sensors. Sources including EF-S and Cinema lenses), the EF mount replaces its predecessor, the FD mount. The standard autofocus lens mounting technology of the time used a motor in the body to drive the mechanics of the focus helicoid in the lens by using a transfer lever. The key innovation of the EF series was to use a motor inside the lens itself for focusing and this allowed for autofocusing lenses which did not require mechanical levers in the mount mechanism, only electrical contacts to supply power and instructions to the lens motor. The motors were designed for the lens they were installed in. When the EF mount was introduced in 1987, it had the largest mount diameter among all 35 mm SLR cameras, the EF series includes over eighty lenses. The EF series has encompassed focal lengths from 8 to 1200 mm, the EF-M mount was introduced with two lenses, a 22mm prime and an 18–55mm zoom. Many EF lenses include such features as Canons ultrasonic motor drive and its large diameter and relatively short flange focal distance of 44.0 mm allows mechanical adaptation of EF camera bodies to many types of non-EF lenses. It is possible to mount lenses using the Nikon F mount, Olympus OM, Leica R, conversely, parfocal adaptation of EF lenses to non-EF camera bodies is not generally possible with only a mechanical adapter that does not contain optical elements.0 mm. Most of these lenses require autofocus and aperture motors inside the body isnt available in EOS bodies. Infinity focus would be lost with an adapter which lacks optical elements, the Canon FD-EOS adapter is rare and is only usable with certain FD telephoto lenses. With a manual connection, the aperture and focus controls of the lens cannot be controlled or read from the camera, since the only possible metering is through-the-lens, the lens must be manually stopped down to accurately meter at anything less than full aperture. With the introduction of the Canon EOS-M mirror-less digital camera, an inexpensive adapter allows the use, including infinity focusing, of nearly all FD. For other lens types, an adapter would act as an extension tube, alternatively, the lens adapters would include optical elements and act as weak teleconverters, as well as possibly losing optical quality
4.
Canon EF-S lens mount
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The Canon EF-S lens mount is a derivative of the EF lens mount created for a subset of Canon digital single-lens reflex cameras with APS-C sized image sensors. Cameras with the EF-S mount are backward compatible with the EF lenses and, such cameras, however, have more clearance, allowing lens elements to be closer to the sensor than in the EF mount. Only Canon cameras released after 2003 with APS-C sized sensors support the EF-S mount, the S in EF-S comes from Small image circle, meaning the lens is designed to provide a small image circle to match the sensor. Although not all Canon EF-S lenses use this short back focus, however, some lenses produced by third-party manufacturers may feature the standard EF mount if they do not require the shorter back focus but only have a small image circle. Such lenses will give noticeable vignetting if used on a 35mm film or full frame sensor cameras, to a lesser degree, vignetting also occurs with APS-H sensor sizes, such as several cameras of the 1D series. The cameras that can use the EF-S mount are, By design, while it is possible to modify the lens such that the physical obstruction is removed, allowing for mounting to EF mount cameras, the rear of the lens would still obstruct the mirror. An additional reason is that the produce a smaller image circle of even illumination. An EF-S lens alignment mark is indicated by a white rectangle. The lens will insert into the body when the alignment marks on each are matched, EF-S camera bodies have both EF-S and EF alignment marks, while EF bodies have only EF marks. Also, attachment of EF-S lenses on EF bodies can often be accomplished by removing the plastic ring seen in the photo above. Although vignetting is still an issue, photos can be taken and this modification comes with caveats, one being that on some lenses, like the EF-S 10-22mm, at the 10mm setting, the element protrudes too far back toward EF mount camera bodies. The variety of EF-S prime lenses is very limited in comparison to EF-S zoom lenses, only two in comparison to 9 zoom lenses. EF-S lenses are popular due to their lower cost and zoom lenses are more preferable by amateur photographers. As of March 2017, no EF-S lens has been produced with the L designation or with diffractive optics, Canon Camera Museum EF Lens Lineup at Canon USA EF/EF-S lens chart EF-S lenses compatible with a 10D
5.
Image sensor
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An image sensor or imaging sensor is a sensor that detects and conveys the information that constitutes an image. It does so by converting the variable attenuation of light waves into signals, the waves can be light or other electromagnetic radiation. As technology changes, digital imaging tends to replace analog imaging, early analog sensors for visible light were video camera tubes. Currently, used types are semiconductor charge-coupled devices or active pixel sensors in complementary metal–oxide–semiconductor or N-type metal-oxide-semiconductor technologies, analog sensors for invisible radiation tend to involve vacuum tubes of various kinds. Digital sensors include flat panel detectors, today, most digital cameras use a CMOS sensor, because CMOS sensors perform better than CCDs. An example is the fact that they incorporate an integrated circuit, CCD is still in use for cheap low entry cameras, but weak in burst mode. Both types of sensor accomplish the task of capturing light. Each cell of a CCD image sensor is an analog device, when light strikes the chip it is held as a small electrical charge in each photo sensor. This process is repeated until all the lines of pixels have had their charge amplified. A CMOS image sensor has an amplifier for each compared to the few amplifiers of a CCD. Some CMOS imaging sensors also use Back-side illumination to increase the number of photons that hit the photodiode, CMOS sensors can potentially be implemented with fewer components, use less power, and/or provide faster readout than CCD sensors. They are also vulnerable to static electricity discharges. Another approach is to utilize the very fine dimensions available in modern CMOS technology to implement a CCD like structure entirely in CMOS technology and this can be achieved by separating individual poly-silicon gates by a very small gap. These hybrid sensors are still in the phase and can potentially harness the benefits of both CCD and CMOS imagers. There are many parameters that can be used to evaluate the performance of a sensor, including dynamic range, signal-to-noise ratio. For sensors of comparable types, the ratio and dynamic range improve as the size increases. In order to avoid interpolated color information, techniques like color co-site sampling use a mechanism to shift the color sensor in pixel steps. 3CCD, using three discrete image sensors, with the color separation done by a dichroic prism, while in general digital cameras use a flat sensor, Sony prototyped a curved sensor in 2014 to reduce/eliminate Petzval field curvature that occurs with a flat sensor
6.
CMOS
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Complementary metal–oxide–semiconductor, abbreviated as CMOS /ˈsiːmɒs/, is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, CMOS technology is also used for several analog circuits such as image sensors, data converters, and highly integrated transceivers for many types of communication. In 1963, while working for Fairchild Semiconductor, Frank Wanlass patented CMOS, CMOS is also sometimes referred to as complementary-symmetry metal–oxide–semiconductor. Two important characteristics of CMOS devices are high noise immunity and low power consumption. Since one transistor of the pair is always off, the series combination draws significant power only momentarily during switching between on and off states, CMOS also allows a high density of logic functions on a chip. It was primarily for this reason that CMOS became the most used technology to be implemented in VLSI chips, aluminium was once used but now the material is polysilicon. Other metal gates have made a comeback with the advent of high-k dielectric materials in the CMOS process, as announced by IBM and Intel for the 45 nanometer node and beyond. CMOS refers to both a style of digital circuitry design and the family of processes used to implement that circuitry on integrated circuits. CMOS circuitry dissipates less power than logic families with resistive loads, since this advantage has increased and grown more important, CMOS processes and variants have come to dominate, thus the vast majority of modern integrated circuit manufacturing is on CMOS processes. As of 2010, CPUs with the best performance per watt each year have been CMOS static logic since 1976, CMOS circuits use a combination of p-type and n-type metal–oxide–semiconductor field-effect transistor to implement logic gates and other digital circuits. CMOS always uses all enhancement-mode MOSFETs, CMOS circuits are constructed in such a way that all PMOS transistors must have either an input from the voltage source or from another PMOS transistor. Similarly, all NMOS transistors must have either an input from ground or from another NMOS transistor, the composition of a PMOS transistor creates low resistance between its source and drain contacts when a low gate voltage is applied and high resistance when a high gate voltage is applied. On the other hand, the composition of an NMOS transistor creates high resistance between source and drain when a low voltage is applied and low resistance when a high gate voltage is applied. CMOS accomplishes current reduction by complementing every nMOSFET with a pMOSFET, a high voltage on the gates will cause the nMOSFET to conduct and the pMOSFET to not conduct, while a low voltage on the gates causes the reverse. This arrangement greatly reduces power consumption and heat generation, however, during the switching time, both MOSFETs conduct briefly as the gate voltage goes from one state to another. This induces a brief spike in consumption and becomes a serious issue at high frequencies. The image on the right shows what happens when an input is connected to both a PMOS transistor and an NMOS transistor, when the voltage of input A is low, the NMOS transistors channel is in a high resistance state. This limits the current that can flow from Q to ground, the PMOS transistors channel is in a low resistance state and much more current can flow from the supply to the output
7.
APS-C
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Advanced Photo System type-C is an image sensor format approximately equivalent in size to the Advanced Photo System classic negatives of 25. 1×16.7 mm, an aspect ratio of 3,2. Sensors approximating these dimensions are used in many digital single-lens reflex cameras, Mirrorless interchangeable-lens cameras, APS-C size sensors are also used in a few digital rangefinders. Such sensors exist in different variants depending on the manufacturer. All APS-C variants are considerably smaller than 35 mm standard film which measures 36×24 mm, sensor sizes range from 20. 7×13.8 mm to 28. 7×19.1 mm, but are typically about 22. 5×15 mm for Canon and 24×16 mm for other manufacturers. Each variant results in a different angle of view from lenses at the same focal length. This is why each manufacturer offers a range of lenses designed for its format, the quality of the image from an APS-C sensor is higher when compared to a smaller sensor due to its larger size which allows it to collect more light. However, compared to a camera, image quality is lower. Most DSLR and third party lens manufacturers now make lenses designed for APS-C cameras. Actual multiplier factor is 1. 255× for the 1D Digital,1. 28× for the Canon EOS-1D Mark III and 1. 29× for the Canon EOS-1D Mark IV. Leica M8 is 1. 33× Canon, Nikon, Pentax, whilst Canon uses a factor of 1. 6×, the other three brands all use 1. 5×. APS-C cameras use an area to form the image than traditional 35 mm cameras. For example, a 28 mm lens is a wide angle lens on a traditional 35 mm camera. But the same lens on an APS-C camera, with a factor of 1. 6×, has the same angle of view as a 45 mm lens on a 35 mm camera—i. e. Several third-party lens manufacturers, such as Tamron, Tokina, and Sigma, Canon introduced the Canon EF-S line of lenses in 2003 alongside the 300D. These lenses place the rear of the closer to the cameras sensor. This has several benefits, including lighter lenses and a field of view. EF-S lenses are compatible with Canons APS-C digital SLRs, with the exception of the early Canon EOS D30, Canon EOS D60, and Canon EOS 10D, EF-S lenses will not physically mount on Canons full-frame digital or 35mm film SLRs. More recently, the introduced the EF-M line for its EOS M series of mirrorless interchangeable-lens cameras
8.
Image resolution
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Image resolution is the detail an image holds. The term applies to digital images, film images. Higher resolution means more image detail, image resolution can be measured in various ways. Resolution quantifies how close lines can be to other and still be visibly resolved. Resolution units can be tied to physical sizes, to the size of a picture. Line pairs are used instead of lines, a line pair comprises a dark line. A line is either a line or a light line. A resolution of 10 lines per millimeter means 5 dark lines alternating with 5 light lines, photographic lens and film resolution are most often quoted in line pairs per millimeter. The resolution of digital cameras can be described in different ways. Resolution is the capability of the sensor to observe or measure the smallest object clearly with distinct boundaries, there is a difference between the resolution and a pixel. A pixel is actually a unit of the digital Resolution depends upon the size of the pixel, usually, with any given lens setting, the smaller the size of the pixel, the higher the resolution will be and the clearer the object in the image will be. Images having smaller pixel sizes might consist of more pixels, the number of pixels correlates to the amount of information within the image. An image of N pixels height by M pixels wide can have any less than N lines per picture height. Other conventions include describing pixels per unit or pixels per area unit. None of these pixel resolutions are true resolutions, but they are referred to as such. Below is an illustration of how the image might appear at different pixel resolutions. An image that is 2048 pixels in width and 1536 pixels in height has a total of 2048×1536 =3,145,728 pixels or 3.1 megapixels, one could refer to it as 2048 by 1536 or a 3. 1-megapixel image. Or, you can think of it as a low quality image if printed at about 28.5 inches wide
9.
Film speed
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Film speed is the measure of a photographic films sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to measure the sensitivity of digital imaging systems, highly sensitive films are correspondingly termed fast films. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality, in short, the higher the sensitivity, the grainier the image will be. Ultimately sensitivity is limited by the efficiency of the film or sensor. The speed of the emulsion was then expressed in degrees Warnerke corresponding with the last number visible on the plate after development. Each number represented an increase of 1/3 in speed, typical speeds were between 10° and 25° Warnerke at the time. The concept, however, was built upon in 1900 by Henry Chapman Jones in the development of his plate tester. In their system, speed numbers were inversely proportional to the exposure required, for example, an emulsion rated at 250 H&D would require ten times the exposure of an emulsion rated at 2500 H&D. The methods to determine the sensitivity were later modified in 1925, the H&D system was officially accepted as a standard in the former Soviet Union from 1928 until September 1951, when it was superseded by GOST 2817-50. The Scheinergrade system was devised by the German astronomer Julius Scheiner in 1894 originally as a method of comparing the speeds of plates used for astronomical photography, Scheiners system rated the speed of a plate by the least exposure to produce a visible darkening upon development. ≈2 The system was extended to cover larger ranges and some of its practical shortcomings were addressed by the Austrian scientist Josef Maria Eder. Scheiners system was abandoned in Germany, when the standardized DIN system was introduced in 1934. In various forms, it continued to be in use in other countries for some time. The DIN system, officially DIN standard 4512 by Deutsches Institut für Normung, was published in January 1934, International Congress of Photography held in Dresden from August 3 to 8,1931. The DIN system was inspired by Scheiners system, but the sensitivities were represented as the base 10 logarithm of the sensitivity multiplied by 10, similar to decibels. Thus an increase of 20° represented an increase in sensitivity. ≈3 /10 As in the Scheiner system, speeds were expressed in degrees, originally the sensitivity was written as a fraction with tenths, where the resultant value 1.8 represented the relative base 10 logarithm of the speed. Tenths were later abandoned with DIN4512, 1957-11, and the example above would be written as 18° DIN, the degree symbol was finally dropped with DIN4512, 1961-10
10.
Computer data storage
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Computer data storage, often called storage or memory, is a technology consisting of computer components and recording media used to retain digital data. It is a function and fundamental component of computers. The central processing unit of a computer is what manipulates data by performing computations, in practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but larger and cheaper options farther away. In the Von Neumann architecture, the CPU consists of two parts, The control unit and the arithmetic logic unit. The former controls the flow of data between the CPU and memory, while the latter performs arithmetic and logical operations on data, without a significant amount of memory, a computer would merely be able to perform fixed operations and immediately output the result. It would have to be reconfigured to change its behavior and this is acceptable for devices such as desk calculators, digital signal processors, and other specialized devices. Von Neumann machines differ in having a memory in which they store their operating instructions, most modern computers are von Neumann machines. A modern digital computer represents data using the numeral system. Text, numbers, pictures, audio, and nearly any form of information can be converted into a string of bits, or binary digits. The most common unit of storage is the byte, equal to 8 bits, a piece of information can be handled by any computer or device whose storage space is large enough to accommodate the binary representation of the piece of information, or simply data. For example, the works of Shakespeare, about 1250 pages in print. Data is encoded by assigning a bit pattern to each character, digit, by adding bits to each encoded unit, redundancy allows the computer to both detect errors in coded data and correct them based on mathematical algorithms. A random bit flip is typically corrected upon detection, the cyclic redundancy check method is typically used in communications and storage for error detection. A detected error is then retried, data compression methods allow in many cases to represent a string of bits by a shorter bit string and reconstruct the original string when needed. This utilizes substantially less storage for many types of data at the cost of more computation, analysis of trade-off between storage cost saving and costs of related computations and possible delays in data availability is done before deciding whether to keep certain data compressed or not. For security reasons certain types of data may be encrypted in storage to prevent the possibility of unauthorized information reconstruction from chunks of storage snapshots. Generally, the lower a storage is in the hierarchy, the lesser its bandwidth and this traditional division of storage to primary, secondary, tertiary and off-line storage is also guided by cost per bit. In contemporary usage, memory is usually semiconductor storage read-write random-access memory, typically DRAM or other forms of fast but temporary storage
11.
Secure Digital
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Secure Digital is a non-volatile memory card format developed by the SD Card Association for use in portable devices. The standard was introduced in August 1999 by joint efforts between SanDisk, Panasonic and Toshiba as an improvement over MultiMediaCards, and has become the industry standard. The three companies formed SD-3C, LLC, a company that licenses and enforces intellectual property rights associated with SD memory cards and SD host, the companies also formed the SD Association, a non-profit organization, in January 2000 to promote and create SD Card standards. SDA today has about 1,000 member companies, the SDA uses several trademarked logos owned and licensed by SD-3C to enforce compliance with its specifications and assure users of compatibility. There are many combinations of factors and device families, although as of 2016. Secure Digital includes four card families available in three different sizes, the four families are the original Standard-Capacity, the High-Capacity, the eXtended-Capacity, and the SDIO, which combines input/output functions with data storage. The three form factors are the size, the mini size, and the micro size. Electrically passive adapters allow a card to fit and function in a device built for a larger card. The SD cards small footprint is a storage medium for smaller, thinner. The second-generation Secure Digital card was developed to improve on the MultiMediaCard standard, which continued to evolve, Secure Digital changed the MMC design in several ways, Asymmetrical slots in the sides of the SD card prevent inserting it upside down. Most SD cards are 2.1 mm thick, compared to 1.4 mm for MMCs. The SD specification defines a card called Thin SD with a thickness of 1.4 mm, the cards electrical contacts are recessed beneath the surface of the card, protecting them from contact with a users fingers. The SD specification envisioned capacities and transfer rates exceeding those of MMC, for a comparison table, see below. While MMC uses a pin for data transfers, the SD card added a four-wire bus mode for higher data rates. The SD card added Content Protection for Recordable Media security circuitry for digital rights management content-protection, full-size SD cards do not fit into the slimmer MMC slots, and other issues also affect the ability to use one format in a host device designed for the other. The Secure Digital High Capacity format, announced in January 2006 and defined in version 2.0 of the SD specification, the SDHC trademark is licensed to ensure compatibility. SDHC cards are physically and electrically identical to standard-capacity SD cards, Version 2.0 also introduces a High-speed bus mode for both SDSC and SDHC cards, which doubles the original Standard Speed clock to produce 25 MB/s. SDHC host devices are required to accept older SD cards, however, older host devices do not recognize SDHC or SDXC memory cards, although some devices can do so through a firmware upgrade
12.
Focus (optics)
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In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent and this non-ideal focusing may be caused by aberrations of the imaging optics. In the absence of significant aberrations, the smallest possible blur circle is the Airy disc, aberrations tend to get worse as the aperture diameter increases, while the Airy circle is smallest for large apertures. An image, or image point or region, is in focus if light from object points is converged almost as much as possible in the image, the border between these is sometimes defined using a circle of confusion criterion. A principal focus or focal point is a focus, For a lens, or a spherical or parabolic mirror. Since light can pass through a lens in either direction, a lens has two focal points—one on each side, the distance in air from the lens or mirrors principal plane to the focus is called the focal length. Elliptical mirrors have two points, light that passes through one of these before striking the mirror is reflected such that it passes through the other. The focus of a mirror is either of two points which have the property that light from one is reflected as if it came from the other. Diverging lenses and convex mirrors do not focus a beam to a point. Instead, the focus is the point from which the light appears to be emanating, a convex elliptical mirror will reflect light directed towards one focus as if it were radiating from the other focus, both of which are behind the mirror. A convex hyperbolic mirror will reflect rays emanating from the point in front of the mirror as if they were emanating from the focal point behind the mirror. Conversely, it can focus rays directed at the point that is behind the mirror towards the focal point that is in front of the mirror as in a Cassegrain telescope. Autofocus Cardinal point Defocus aberration Depth of field Depth of focus Far point Focus Fixed focus Bokeh Focus stacking Focal Plane
13.
Exposure (photography)
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In photography, exposure is the amount of light per unit area reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance. Exposure is measured in lux seconds, and can be computed from exposure value, in photographic jargon, an exposure generally refers to a single shutter cycle. For the same speed, the accumulated photometric exposure should be similar in both cases. A photograph may be described as underexposed when it has a loss of detail, that is. As the adjacent image shows, these terms are technical ones, there are three types of settings, manual, automatic and exposure compensation. Radiant exposure of a surface, denoted He and measured in J/m2, is given by H e = E e t, where Ee is the irradiance of the surface, measured in W/m2, t is the exposure duration, measured in s. Luminous exposure of a surface, denoted Hv and measured in lx⋅s, is given by H v = E v t, many photographic materials are also sensitive to invisible light, which can be a nuisance, or a benefit. The use of units is appropriate to characterize such sensitivity to invisible light. In sensitometric data, such as curves, the log exposure is conventionally expressed as log10. Photographers more familiar with base-2 logarithmic scales can convert using log2 ≈3.32 log10, correct exposure may be defined as an exposure that achieves the effect the photographer intended. A more technical approach recognises that a film has a physically limited useful exposure range. If, for any part of the photograph, the exposure is outside this range. In a very simple model, for example, out-of-range values would be recorded as black or white rather than the precisely graduated shades of colour and this ensures that no significant information is lost during capture. However, it is much easier to discard recorded information during post processing than to try to re-create unrecorded information. In a scene with strong or harsh lighting, the ratio between highlight and shadow luminance values may well be larger than the ratio between the maximum and minimum useful exposure values. A photograph may be described as underexposed when it has a loss of detail, that is. In manual mode, the photographer adjusts the lens aperture and/or shutter speed to achieve the desired exposure, manual exposure calculations may be based on some method of light metering with a working knowledge of exposure values, the APEX system and/or the Zone System. A camera in automatic exposure mode automatically calculates and adjusts exposure settings to match the subjects mid-tone to the mid-tone of the photograph, for most cameras this means using an on-board TTL exposure meter
14.
Light metering
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A light meter is a device used to measure the amount of light. In photography, a meter is often used to determine the proper exposure for a photograph. Light meters are used in the fields of cinematography and scenic design. They are used in the field of lighting, where they can help to reduce the amount of waste light used in the home, light pollution outdoors. The earliest type of light meters were called extinction meters and contained a numbered or lettered row of neutral density filters of increasing density. The photographer would position the meter in front of his subject, the letter or number corresponding to the filter was used as an index into a chart of appropriate aperture and shutter speed combinations for a given film speed. Extinction meters suffered from the problem that they depended on the sensitivity of the human eye. Later meters removed the element and relied on technologies incorporating selenium, CdS. Selenium and silicon light meters use sensors that are photovoltaic, they generate a proportional to light exposure. Selenium sensors generate enough voltage for direct connection to a meter, they need no battery to operate, selenium sensors however cannot measure low light accurately and are altogether unable to measure very low light, such as candlelight, moonlight, starlight etc. Silicon sensors need an amplification circuit and require a source such as batteries to operate. CdS light meters use a sensor based on photoresistance, i. e. their electrical resistance changes proportionately to light exposure and these also require a battery to operate. Most modern light meters use silicon or CdS sensors and they indicate the exposure either with a needle galvanometer or on an LCD screen. Many modern consumer still and video include a built-in meter that measures a scene-wide light level and are able to make an approximate measure of appropriate exposure based on that. There are two types of light meters, reflected-light and incident-light. Reflected-light meters measure the light reflected by the scene to be photographed, all in-camera meters are reflected-light meters. Reflected-light meters are calibrated to show the appropriate exposure for “average” scenes and this pitfall is avoided by incident-light meters which measure the amount of light falling on the subject using an integrating sphere placed on top of the light sensor. Because the incident-light reading is independent of the reflectance, it is less likely to lead to incorrect exposures for subjects with unusual average reflectance
15.
Metering mode
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In photography, the metering mode refers to the way in which a camera determines the exposure. Cameras generally allow the user to select between spot, center-weighted average, or multi-zone metering modes, various metering modes are provided to allow the user to select the most appropriate one for use in a variety of lighting conditions. With spot metering, the camera will only measure a small area of the scene. This will by default be the centre of the scene. The user can select a different off-centre spot, or to recompose by moving the camera after metering. The first spot meter was built by Arthur James Dalladay, editor of The British Journal of Photography in about 1935, a few models support a Multi-Spot mode which allows multiple spot meter readings to be taken of a scene that are averaged. Some cameras, the OM-4 and T90 included, also support metering of highlight, spot metering is very accurate and is not influenced by other areas in the frame. It is commonly used to very high contrast scenes. The area around the back and hairline will then become over-exposed, spot metering is a method upon which the Zone System depends. In many cases the camera will over or underexpose, when using the spot mode, modern cameras tend to find the correct exposure precisely. In complex light situations though, professional photographers tend to switch to manual mode, another example of spot metering usage would be when photographing the moon. Due to the dark nature of the scene, other metering methods tend to overexpose the moon. Spot metering will allow for more detail to be out in the moon while underexposing the rest of the scene. More commonly, spot metering is used in photography, where the brightly lit actors stand before a dark or even black curtain or scrim. Spot metering only considers the actors in this case, while ignoring the overall darkness of the scene, in this system, the meter concentrates between 60 to 80 percent of the sensitivity towards the central part of the viewfinder. The balance is then feathered out towards the edges, some cameras will allow the user to adjust the weight/balance of the central portion to the peripheral one. When moving the point off center the camera will proceed as above. Although promoted as a feature, center-weighted metering was originally a consequence of the meter cell reading from the screen of SLR cameras
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Flash (photography)
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A flash is a device used in photography producing a flash of artificial light at a color temperature of about 5500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene, other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs, modern cameras often activate flash units automatically. Flash units are built directly into a camera. Some cameras allow separate flash units to be mounted via an accessory mount bracket. In professional studio equipment, flashes may be large, standalone units, or studio strobes, studies of magnesium by Bunsen and Roscoe in 1859 showed that burning this metal produced a light with similar qualities to daylight. The potential application to photography inspired Edward Sonstadt to investigate methods of manufacturing magnesium so that it would burn reliably for this use and he applied for patents in 1862 and by 1864 had started the Manchester Magnesium Company with Edward Mellor. It also had the benefit of being a simpler and cheaper process than making round wire, mather was also credited with the invention of a holder for the ribbon, which formed a lamp to burn it in. The packaging also implies that the ribbon was not necessarily broken off before being ignited. An alternative to ribbon was flash powder, a mixture of powder and potassium chlorate, introduced by its German inventors Adolf Miethe. A measured amount was put into a pan or trough and ignited by hand, producing a brilliant flash of light, along with the smoke. This could be an activity, especially if the flash powder was damp. An electrically triggered flash lamp was invented by Joshua Lionel Cowen in 1899 and his patent describes a device for igniting photographers’ flash powder by using dry cell batteries to heat a wire fuse. Variations and alternatives were touted from time to time and a few found a measure of success in the marketplace, especially for amateur use. The use of powder in an open lamp was replaced by flashbulbs, magnesium filaments were contained in bulbs filled with oxygen gas. Manufactured flashbulbs were first produced commercially in Germany in 1929, such a bulb could only be used once, and was too hot to handle immediately after use, but the confinement of what would otherwise have amounted to a small explosion was an important advance. A later innovation was the coating of flashbulbs with a film to maintain bulb integrity in the event of the glass shattering during the flash
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Canon EOS flash system
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Canon Inc. s EOS flash system refers to the photographic flash mechanism used on Canons film or digital EOS single-lens reflex cameras. The line was first introduced in 1987 and it has gone through a number of revisions over the years, as new flash exposure metering systems have been introduced. The main light-metering technologies are known as A-TTL, E-TTL, the EOS flash system is capable of wireless multiple flash control, whereby a master flash unit IR or RF transmitter mounted on the camera body can control up to 3 or 5 groups of flash units. The 7D is capable of handling three slave groups, the other cameras can handle two slave groups. Canon has introduced several different metering systems for its products, A-TTL, E-TTL. Each system represents different approaches to achieving the proper flash exposure, A-TTL is an initialism that stands for Advanced-Through The Lens flash metering. As with ordinary TTL flash exposure systems, a sensor inside the camera reads the amount of light being reflected off the film during the exposure, when the sensor determines that the exposure is sufficient, it terminates the flash pulse. A-TTL, first seen on the T90, is an exposure system that adds a brief preflash during exposure metering when the camera is in the programmed exposure mode. The amount of light returned from this preflash is used to determine an appropriate tradeoff between aperture and shutter speed in P mode. Depending on the flash unit and whether or not it is set to bounce. E-TTL is a Canon EOS flash exposure system that uses a brief pre-flash before the flash in order to obtain a more correct exposure. Unlike TTL and A-TTL metering, which use a dedicated flash metering sensor mounted in the base of the mirror box, the pre-flash occurs immediately before the main flash and is barely perceptible, although it can be seen if you watch carefully for it. The pre-flash may cause undesirable reactions from animate objects - e. g. humans may blink as a reaction to the pre-flash, when using flash exposure lock, the pre-flash is fired when FEL is activated. E-TTL II is an improvement on E-TTL and is now a standard in all EOS cameras introduced with or after the Canon EOS-1D Mark II in 2004. E-TTL II is implemented in the body, not the flash unit, the main improvement of E-TTL II is that it gives a more natural flash exposure, by being able to handle tricky scenes where the old E-TTL system would normally be thrown off. The flash metering system is no longer linked to the AF system, whereas in the old E-TTL metering. Rather, E-TTL II compares the ambient and the light levels of the scene to determine where the subject lies. This gives the photographer the flexibility to focus and recompose the scene without fooling the flash metering system
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Bracketing
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In photography, bracketing is the general technique of taking several shots of the same subject using different camera settings. Autobracketing is automatic bracketing by using a setting on the camera to take several bracketed shots, given the time it takes to accomplish multiple shots, it is typically, but not always, used for static subjects. Technically, this can be accomplished by changing either the speed or the aperture, or, with digital cameras. Exposure can also be changed by altering the level, for example using neutral-gray filters or changing the degree of illumination of the subject. Exposure bracketing is indicated when dealing with high-contrast subjects and/or media with limited dynamic range, exposure bracketing is also used to create fade-in or fade-out effects, for example in conjunction with multi-vision slide shows, or in combination with multiple exposure or flash. When shooting using negative film, the printing the pictures to paper must not compensate for the deliberately underexposed and overexposed pictures. Images produced using exposure bracketing are often combined in postprocessing to create a dynamic range image that exposes different portions of the image by different amounts. Flash bracketing is a technique of working with electronic flash, especially used as fill flash in combination with existing light. The amount of light provided by the flash is varied in a series in order to find the most pleasing combination of ambient light. If used for purpose, flash bracketing can be differentiated from normal exposure bracketing via flash. Alternatively, if the amount of light cannot be altered easily, it is also possible to alter the aperture instead, however. In the first case, it will change the amount of motion blur in the picture. In the second case, it may visibly affect image noise, combining DOF bracketing with multiple exposure, the so-called STF effect can be achieved as implemented in the Minolta Maxxum 7s automated STF function. This closely resembles the Bokeh-pleasing optical effect of the filter in the Minolta/Sony STF135 mm f/2.8 s special-purpose lens. Usually this involves the use of software with unsharp masking, an algorithm that removes out-of-focus portions of each exposure. The in-focus portions are then stacked, combined into a single image, focus stacking is challenging, in that the subject must stay still and that as the focal point changes, the magnification of the images change. This must then be corrected in an application by transforming the image. ISO bracketing is a form of simulated exposure bracketing in which aperture and this is analogous to pushing or pulling in film processing, and as in film processing, will affect the amount of grain or image noise
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Shutter (photography)
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A shutter can also be used to allow pulses of light to pass outwards, as seen in a movie projector or a signal lamp. A shutter of variable speed is used to control exposure time of the film, the shutter is so constructed that it automatically closes after a certain required time interval. The speed of the shutter is controlled by a ring outside the camera, focal-plane shutters are mounted near the focal plane and move to uncover the film or sensor. Behind-the-lens shutters were used in cameras with limited lens interchangeability. Shutters in front of the lens, sometimes simply a lens cap that is removed and replaced for the long exposures required, were used in the days of photography. Other mechanisms than the aperture and the sliding curtains have been used. The time for which a shutter remains open is determined by a timing mechanism and these were originally pneumatic or clockwork, but since the late twentieth century are mostly electronic. The reciprocal of time in seconds is often used for engraving shutter settings. For example, a marking of 250 denotes 1/250 and this does not cause confusion in practice. The exposure time and the aperture of the lens must together be such as to allow the right amount of light to reach the film or sensor. Additionally, the time must be suitable to handle any motion of the subject. Usually it must be fast enough to freeze rapid motion, unless a controlled degree of motion blur is desired, most shutters have a flash synchronization switch to trigger a flash, if connected. This was quite a complicated matter with mechanical shutters and flashbulbs which took a time to reach full brightness. Special flashbulbs were designed which had a burn, illuminating the scene for the whole time taken by a focal plane shutter slit to move across the film. These problems were solved for non-focal-plane shutters with the advent of electronic flash units which fire virtually instantaneously. When using a focal-plane shutter with a flash, if the shutter is set at its X-sync speed or slower the whole frame will be exposed when the flash fires, some electronic flashes can produce a longer pulse compatible with a focal-plane shutter operated at much higher shutter speeds. The focal-plane shutter will still impart focal-plane shutter distortions to a moving subject. Cinematography uses a rotary shutter in movie cameras, a continuously spinning disc which conceals the image with a reflex mirror during the intermittent motion between frame exposure
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Focal-plane shutter
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For slower shutter speeds, the first curtain opens from right to left, and after the required time with the shutter open, the second curtain closes the aperture in the same direction. When the shutter is cocked again the shutter curtains are moved back to their starting positions, focal-plane shutter at low speed Figure 1, The black rectangle represents the frame aperture through which the exposure is made. It is currently covered by the first shutter curtain, shown in red, the second shutter curtain shown in green is on the right side. Figure 2, The first shutter curtain moves fully to the left allowing the exposure to be made, at this point the flash is made to fire if one is attached and ready to do so. Figure 3, After the required amount of exposure the second shutter curtain moves to the left to cover the frame aperture, when the shutter is recocked the shutter curtains are wound back to the right hand side ready for the next exposure. This is a graphical representation only, the mechanisms are much more complex. For example, the shutter curtains actually roll on and off spools at either side of the aperture so as to use as little space as possible. Faster shutter speeds are achieved by the second curtain closing before the first one has fully opened, faster shutter speeds simply require a narrower slit, as the speed of travel of the shutter curtains is not normally varied. Using this technique, modern SLR cameras are capable of speeds of up to 1/2000, 1/4000 or even 1/8000 of a second. Focal-plane shutter at high speed Figure 1, The black rectangle represents the frame aperture through which the exposure is made and it is currently covered by the first shutter curtain, shown in red. The second shutter curtain shown in green is on the right side, Figure 2, The first shutter curtain begins to move to the left allowing the exposure to be made. Because the exposure requires a very fast shutter speed, the second curtain begins to move across at a set distance from the first one, Figure 3, The first shutter curtain continues to travel across the frame aperture followed by the second curtain. Figure 4, The first shutter curtain finishes moving, followed closely by the curtain which is now covering the frame aperture completely. When the shutter is recocked both shutter curtains are wound back to the hand side ready for the next exposure. Most modern 35 mm and digital SLR cameras now use vertical travel metal blade shutters. These work in precisely the way as the horizontal shutters, but because of the shorter distance the shutter blades must travel. This can result in faster flash synchronization speeds than are possible with the horizontal-curtain focal-plane shutter, another advantage of the focal-plane shutter is that their fastest speeds are quite high, 1/4000 second or even 1/8000 second, much higher than the 1/500 second of the typical leaf shutter. The main disadvantage of the shutter is that a durable and reliable one is a complex device
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Shutter speed
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The amount of light that reaches the film or image sensor is proportional to the exposure time. 1/500th of a second will let half as much light in as 1/250th, the cameras shutter speed, the lenss aperture, and the scenes luminance together determine the amount of light that reaches the film or sensor. Exposure value is a quantity that accounts for the shutter speed and this will achieve a good exposure when all the details of the scene are legible on the photograph. Too much light let into the results in an overly pale image while too little light will result in an overly dark image. Multiple combinations of speed and f-number can give the same exposure value. According to exposure value formula, doubling the exposure time doubles the amount of light, for example, f/8 lets 4 times more light into the camera as f/16 does. In addition to its effect on exposure, the speed changes the way movement appears in photographs. Very short shutter speeds can be used to freeze fast-moving subjects, very long shutter speeds are used to intentionally blur a moving subject for effect. Short exposure times are called fast, and long exposure times slow. Adjustments to the aperture need to be compensated by changes of the speed to keep the same exposure. The agreed standards for shutter speeds are, With this scale, camera shutters often include one or two other settings for making very long exposures, B keeps the shutter open as long as the shutter release is held. T keeps the open until the shutter release is pressed again. The ability of the photographer to take images without noticeable blurring by camera movement is an important parameter in the choice of the slowest possible speed for a handheld camera. Through practice and special techniques such as bracing the camera, arms, or body to minimize movement, using a monopod or a tripod. If a shutter speed is too slow for hand holding, a support, usually a tripod. Image stabilization on digital cameras or lenses can often permit the use of shutter speeds 3–4 stops slower, Shutter priority refers to a shooting mode used in cameras. It allows the photographer to choose a shutter speed setting and allow the camera to decide the correct aperture and this is sometimes referred to as Shutter Speed Priority Auto Exposure, or TV mode, S mode on Nikons and most other brands. Shutter speed is one of methods used to control the amount of light recorded by the cameras digital sensor or film
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Flash synchronization
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In a camera, flash synchronization is defined as synchronizing the firing of a photographic flash with the opening of the shutter admitting light to photographic film or electronic image sensor. It is often shortened to flash sync or flash synch, in electronic digital cameras, the mechanism is usually a programmable electronic timing circuit, which may, in some cameras, take input from a mechanical shutter contact. The flash is connected electrically to the camera either by a cable with a standardised coaxial PC3.5 mm connector, or via contacts in an accessory mount bracket. X-sync is the simplest to explain and implement, the flash is fired at the instant the shutter is fully open and these sync modes close the contacts a few milliseconds before the shutter is open, to give the flashbulb time to reach peak brightness before exposing the film. Class M bulbs reach their peak illumination at around 20-25 milliseconds after ignition, most standard flash bulbs used M sync. X sync closes the flash contact just as the blades are almost completely open. FP sync was used with FP flash bulbs designed specifically for use with focal-plane shutters, FP bulbs burned close to full brightness for the full X-sync time, exposing the whole frame even at high shutter speeds. The Nikon F offered FP, M, and ME bulb synchronizations, X sync is a mode designed for use with electronic flash. In this mode, the timing of the contacts coincides exactly with the opening of the shutter. Special electronic flash units for focal-plane shutters fire several times as the slit moves across the film, electronic shutters used in some digital cameras do not have this limitation and may allow a very high X-sync speed. Leaf shutters, which are situated within the lens housing, open to expose the entire image at once. The Friedrich Deckel Synchro-Compur leaf shutter of the Braun Paxette Reflex offered V, X, higher sync speeds are useful as they enable the brightness of the background to be controlled while maintaining normal flash exposure in the foreground, for example with a back-lit subject. Today, certain modern xenon flash units have the ability to produce a flash to permit flash synchronization at shorter shutter speeds. Instead of delivering one burst of light, the units deliver several smaller bursts over an interval as short as 1/125 of a second. This allows light to be delivered to the area of the film or image sensor even though the shutter is never fully open at any moment. The downside is that the flash is of less effective intensity since the individual bursts are lower powered than the capability of the flash unit. Wireless remote flash triggers with these features are becoming more common and this mode is called either rear-curtain sync or 2nd-curtain sync. The first camera to implement a flash synchronizer was the Exakta, some synchronization methods employ optical or radio triggering that requires no electrical connection to the camera or main flash unit
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Burst mode (photography)
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Burst or continuous high speed is a shooting mode in still cameras. In burst mode several photographs are captured in succession by either pressing the shutter button or holding it down. This is used mainly when the subject is in successive motion, the photographer can then select the best image of the group or arrange them in a sequence to study the transitions in detail. The speed at which successive photographs can be captured depends on several factors, disabling certain features such as post processing which the camera applies automatically after capturing each image will usually allow a faster rate of capture. Frames per second tells the rate at which a camera is taking photos, burst rate tells how many frames can be taken in quick succession, before the frame rate slows down. Cameras capable of continuous shooting rates are much desired when the subjects are in motion, as in sports photography. Rather than anticipate the action precisely, photographers can simply start shooting from right before they believe the action will occur, the Panasonic Lumix DMC-GH2 is capable of recording 40 still images per second in burst mode, at a slightly reduced resolution. The claim is among digital cameras with interchangeable lenses, most high-end camera phones and some mid-range phones, and a few low end ones, provide burst shooting. For example, the Samsung Galaxy SIII Mini can capture 20 photos continuously at 3.3 fps by tapping and holding the shutter button. Other examples include, Samsung Galaxy Note 3 at 4-5 fps, Apple iPhone 5S at 10 fps, or up to 30 fps with special software, and the ASUS Padfone Mini at 16fps
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Viewfinder
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In photography, a viewfinder is what the photographer looks through to compose, and, in many cases, to focus the picture. Most viewfinders are separate, and suffer parallax, while the single-lens reflex camera lets the use the main optical system. Viewfinders are used in many cameras of different types, still and movie, film, analog, a zoom camera usually zooms its finder in sync with its lens, one exception being rangefinder cameras. Before the development of microelectronics and electronic devices, only optical viewfinders existed. Direct viewfinders are essentially miniature Galilean telescopes, the eye was placed at the back. A declining minority of point and shoot cameras use them, parallax error results from the viewfinder being offset from the lens axis, to point above and usually to one side of the lens. The error varies with distance, being negligible for distant scenes, viewfinders often show lines to indicate the edge of the region which would be included in the photograph. Cameras with interchangeable lenses had to indicate the field of view of each lens in the viewfinder, more usually, such viewfinders were integrated into box cameras, and fitted to the side of folding cameras. These viewfinders were fitted to inexpensive cameras, for many sports and press applications optical viewfinders gave too small an image and were inconvenient to use for scenes that were changing rapidly. This was fast and convenient to use, but not particularly accurate, twin-lens reflex cameras had a large lens above the taking lens, and a large mirror at 45°, projecting an image onto a ground glass screen viewable from above, with the camera at waist level. The viewfinder lens was of size and focal length to the taking lens, though the optical quality was less critical. These cameras were expensive, the Rolleiflex and cheaper sister Rolleicord were the pioneers. Both single- and twin-lens reflexes allowed focussing by adjusting the lens until the image was sharp, single-lens reflex cameras viewed the scene through the taking lens. Early SLRs were plate cameras, with a mechanism to insert a mirror between the lens and the film reflected the light upwards, where it could be seen at waist level on a ground glass screen. When ready to take the picture, the mirror was pivoted out of the way, later SLRs had a mechanism which flipped the mirror out of the way when the shutter button was pressed, followed immediately by the shutter opening. Instead of an arrangement, a prism was used to allow the camera to be held to the eye. The big advantage of the SLR was that any lens, or other device, could be used. The live preview feature of digital cameras share this advantage of the SLR, as they show the image exactly as it will be recorded
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Color balance
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In photography and image processing, color balance is the global adjustment of the intensities of the colors. An important goal of this adjustment is to specific colors – particularly neutral colors – correctly. Hence, the method is sometimes called gray balance, neutral balance. Color balance changes the mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to change them for effect. Image data acquired by sensors – either film or electronic image sensors – must be transformed from the values to new values that are appropriate for color reproduction or display. In film photography, color balance is achieved by using color correction filters over the lights or on the camera lens. It is particularly important that neutral colors in a scene appear neutral in the reproduction, most digital cameras have means to select color correction based on the type of scene lighting, using either manual lighting selection, automatic white balance, or custom white balance. The algorithms for these processes perform generalized chromatic adaptation, many methods exist for color balancing. Setting a button on a camera is a way for the user to indicate to the processor the nature of the scene lighting, another option on some cameras is a button which one may press when the camera is pointed at a gray card or other neutral colored object. This captures an image of the ambient light, which enables a digital camera to set the color balance for that light. There is a literature on how one might estimate the ambient lighting from the camera data. A variety of algorithms have been proposed, and the quality of these has been debated, a few examples and examination of the references therein will lead the reader to many others. Examples are Retinex, a neural network or a Bayesian method. Color balancing an image not only the neutrals, but other colors as well. An image that is not color balanced is said to have a color cast, Color balancing may be thought in terms of removing this color cast. Color balance is related to color constancy. Algorithms and techniques used to color constancy are frequently used for color balancing
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Battery pack
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A battery pack is a set of any number of identical batteries or individual battery cells. They may be configured in a series, parallel or a mixture of both to deliver the desired voltage, capacity, or power density, the term battery pack is often used in reference to RC hobby toys and battery electric vehicles. Components of battery packs include the batteries or cells. Rechargeable battery packs contain a temperature sensor, which the battery charger uses to detect the end of charging. Interconnects are also found in batteries as they are the part which connects each cell, when a pack contains groups of cells in parallel there are differing wiring configurations which take into consideration the electrical balance of the circuit. Active balancing can also be performed by battery balancer devices which can shuttle energy from strong cells to weaker ones in time for better balance. A well-balanced pack lasts longer and delivers better performance, for an inline package, cells are selected and stacked with solder in between them. The cells are pressed together and a current pulse generates heat to them together. SOC or State of charge is the equivalent of a gauge for a battery. SOC cannot be determined by a voltage measurement, because the terminal voltage of a battery may stay substantially constant until it is completely discharged. More complex state of charge estimation systems take into account the Peukert effect which relates the capacity of the battery to the discharge rate, an advantage of a battery pack is the ease with which it can be swapped into or out of a device. This allows multiple packs to deliver extended runtimes, freeing up the device for continued use while charging the removed pack separately. Another advantage is the flexibility of their design and implementation, allowing the use of cheaper high-production cells or batteries to be combined into a pack for nearly any application. At the end of life, batteries can be removed and recycled separately. Packs are often simpler for end users to repair or tamper with than a sealed non-serviceable battery or cell. Though some might consider this an advantage it is important to safety precautions when servicing a battery pack as they pose a danger as potential chemical, electrical
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Dimension
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In physics and mathematics, the dimension of a mathematical space is informally defined as the minimum number of coordinates needed to specify any point within it. Thus a line has a dimension of one only one coordinate is needed to specify a point on it – for example. The inside of a cube, a cylinder or a sphere is three-dimensional because three coordinates are needed to locate a point within these spaces, in classical mechanics, space and time are different categories and refer to absolute space and time. That conception of the world is a space but not the one that was found necessary to describe electromagnetism. The four dimensions of spacetime consist of events that are not absolutely defined spatially and temporally, Minkowski space first approximates the universe without gravity, the pseudo-Riemannian manifolds of general relativity describe spacetime with matter and gravity. Ten dimensions are used to string theory, and the state-space of quantum mechanics is an infinite-dimensional function space. The concept of dimension is not restricted to physical objects, high-dimensional spaces frequently occur in mathematics and the sciences. They may be parameter spaces or configuration spaces such as in Lagrangian or Hamiltonian mechanics, in mathematics, the dimension of an object is an intrinsic property independent of the space in which the object is embedded. This intrinsic notion of dimension is one of the ways the mathematical notion of dimension differs from its common usages. The dimension of Euclidean n-space En is n, when trying to generalize to other types of spaces, one is faced with the question what makes En n-dimensional. One answer is that to cover a ball in En by small balls of radius ε. This observation leads to the definition of the Minkowski dimension and its more sophisticated variant, the Hausdorff dimension, for example, the boundary of a ball in En looks locally like En-1 and this leads to the notion of the inductive dimension. While these notions agree on En, they turn out to be different when one looks at more general spaces, a tesseract is an example of a four-dimensional object. The rest of this section some of the more important mathematical definitions of the dimensions. A complex number has a real part x and an imaginary part y, a single complex coordinate system may be applied to an object having two real dimensions. For example, an ordinary two-dimensional spherical surface, when given a complex metric, complex dimensions appear in the study of complex manifolds and algebraic varieties. The dimension of a space is the number of vectors in any basis for the space. This notion of dimension is referred to as the Hamel dimension or algebraic dimension to distinguish it from other notions of dimension
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Mass
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In physics, mass is a property of a physical body. It is the measure of a resistance to acceleration when a net force is applied. It also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram, Mass is not the same as weight, even though mass is often determined by measuring the objects weight using a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity and this is because weight is a force, while mass is the property that determines the strength of this force. In Newtonian physics, mass can be generalized as the amount of matter in an object, however, at very high speeds, special relativity postulates that energy is an additional source of mass. Thus, any body having mass has an equivalent amount of energy. In addition, matter is a defined term in science. There are several distinct phenomena which can be used to measure mass, active gravitational mass measures the gravitational force exerted by an object. Passive gravitational mass measures the force exerted on an object in a known gravitational field. The mass of an object determines its acceleration in the presence of an applied force, according to Newtons second law of motion, if a body of fixed mass m is subjected to a single force F, its acceleration a is given by F/m. A bodys mass also determines the degree to which it generates or is affected by a gravitational field and this is sometimes referred to as gravitational mass. The standard International System of Units unit of mass is the kilogram, the kilogram is 1000 grams, first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the prototype kilogram. As of January 2013, there are proposals for redefining the kilogram yet again. In this context, the mass has units of eV/c2, the electronvolt and its multiples, such as the MeV, are commonly used in particle physics. The atomic mass unit is 1/12 of the mass of a carbon-12 atom, the atomic mass unit is convenient for expressing the masses of atoms and molecules. Outside the SI system, other units of mass include, the slug is an Imperial unit of mass, the pound is a unit of both mass and force, used mainly in the United States
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Country of origin
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Country of origin, is the country of manufacture, production, or growth where an article or product comes from. There are differing rules of origin under various laws and international treaties. The effects of country of origin labeling on consumer purchasing have been extensively studied The country of origin effect is known as the made-in image. Its effect is strongest on consumers who dont know much about the product or product type, sensitivity to country of origin varies by product category. It is strongest for durable goods and luxury goods and weakest for low involvement product categories such as shampoo, in various studies it has also been proven that the Country-of-Origin Effect also applies to services. The requirements for Country of Origin markings are complicated by the various designations which may be required such as Made in X, Product of X and they also vary by country of import and export. For example, For imports to the United Kingdom, there is a code for Food. Other products are not subject to labelling requirements, but misleading labelling can result in prosecution under the Trade Descriptions Act 1968, meats, produce, and several other raw agricultural products generally were exempt. Textile products that are imported must be labeled as required by the Customs Service, a textile or wool product partially manufactured in the U. S. and partially manufactured in another country must be labeled to show both foreign and domestic processing. On a garment without a neck and on other kinds of textile products, catalogs and other mail order promotional materials for textile and wool products, including those disseminated on the Internet, must disclose whether a product is made in the U. S. imported, or both. The Fur Products Labeling Act requires the country of origin of imported furs to be disclosed on all labels, any representation that a car marketer makes that is required by the AALA is exempt from the Commission’s policy. When a company makes claims in advertising or promotional materials that go beyond the AALA requirements, it will be held to the Commission’s standard. The Buy American Act requires that a product be manufactured in the U. S. of more than 50 percent U. S. parts to be considered Made in USA for government procurement purposes. For more information, review the Buy American Act at 41 U. S. C. §§ 10a-10c, part 25, and the Trade Agreements Act at 19 U. S. C. The Lanham Act gives any person who is damaged by a designation of origin the right to sue the party making the false claim. Companies may indicate with a number of different strategies, though not all of these legal requirements in all jurisdictions. Use of the phrase Made in, Country of origin will affect its admissibility, the rate of duty, its entitlement to special duty or trade preference programs, antidumping, and government procurement. Today, many products are an outcome of a number of parts and pieces that come from many different countries
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Taiwan
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Taiwan, officially the Republic of China, is a state in East Asia. Neighbours include China to the west, Japan to the northeast, Taiwan is the most populous state that is not a member of the United Nations, and the one with the largest economy. The island of Taiwan, also known as Formosa, was inhabited by Taiwanese aborigines before the 17th century. After a brief rule by the Kingdom of Tungning, the island was annexed by the Qing dynasty, the Qing ceded Taiwan to Japan in 1895 after the Sino-Japanese War. While Taiwan was under Japanese rule, the Republic of China was established on the mainland in 1912 after the fall of the Qing dynasty, following the Japanese surrender to the Allies in 1945, the ROC took control of Taiwan. However, the resumption of the Chinese Civil War led to the ROCs loss of the mainland to the Communists, and the flight of the ROC government to Taiwan in 1949. As a founding member of the United Nations, the ROC continued to represent China at the United Nations until 1971, in the early 1960s, Taiwan entered a period of rapid economic growth and industrialization, creating a stable industrial economy. In the 1980s and early 1990s, it changed from a one-party military dictatorship dominated by the Kuomintang to a multi-party democracy with universal suffrage, Taiwan is the 22nd-largest economy in the world, and its high-tech industry plays a key role in the global economy. It is ranked highly in terms of freedom of the press, health care, public education, economic freedom, the PRC has consistently claimed sovereignty over Taiwan and asserted the ROC is no longer in legitimate existence. Under its One-China Policy the PRC refused diplomatic relations with any country that recognizes the ROC, the PRC has threatened the use of military force in response to any formal declaration of independence by Taiwan or if PRC leaders decide that peaceful unification is no longer possible. There are various names for the island of Taiwan in use today, the former name Formosa dates from 1542, when Portuguese sailors sighted the main island of Taiwan and named it Ilha Formosa, which means beautiful island. The name Formosa eventually replaced all others in European literature and was in use in English in the early 20th century. This name was adopted into the Chinese vernacular as the name of the sandbar. The modern word Taiwan is derived from this usage, which is seen in forms in Chinese historical records. Use of the current Chinese name was formalized as early as 1684 with the establishment of Taiwan Prefecture, through its rapid development, the entire Formosan mainland eventually became known as Taiwan. The official name of the state is the Republic of China and it was a member of the United Nations representing China until 1971, when it lost its seat to the Peoples Republic of China. Over subsequent decades, the Republic of China has become known as Taiwan. In some contexts, especially ones from the ROC government
31.
Canon Inc.
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It is headquartered in Ōta, Tokyo, Japan. Canon has a listing on the Tokyo Stock Exchange and is a constituent of the TOPIX index. It has a listing on the New York Stock Exchange. At the beginning of 2015, Canon was the tenth largest public company in Japan when measured by market capitalization, the company was originally named Seikikōgaku kenkyūsho. In 1934 it produced the Kwanon, a prototype for Japan’s first-ever 35 mm camera with a plane based shutter. In 1947 the company name was changed to Canon Camera Co. Inc. shortened to Canon Inc. in 1969, the name Canon comes from Buddhist bodhisattva Guan Yin, previously transliterated as Kuanyin, Kwannon, or Kwanon in English. The origins of Canon date back to the founding of Precision Optical Instruments Laboratory in Japan in 1937 by Takeshi Mitarai, Goro Yoshida, Saburo Uchida and Takeo Maeda. During its early years the company did not have any facilities to produce its own optical glass, between 1933 and 1936 ‘The Kwanon’, a copy of the Leica design, Japan’s first 35 mm focal plane-shutter camera, was developed in prototype form. In 1940 Canon developed Japans first indirect X-ray camera, Canon introduced a field zoom lens for television broadcasting in 1958 and in 1959 introduced the Reflex Zoom 8, the world’s first movie camera with a zoom lens, and the Canonflex. In 1961 Canon introduced the Rangefinder camera, Canon 7, in 1965 Canon introduced the Canon Pellix, a single lens reflex camera with a semi-transparent stationary mirror which enabled the taking of pictures through the mirror. In 1971 Canon introduced the F-1, a high-end SLR camera, in 1976 Canon launched the AE-1, the world’s first camera with an embedded micro-computer. In 1982 Wildlife as Canon Sees It print ads first appeared in National Geographic magazine, Canon introduced the world’s first Inkjet printer using bubble jet technology in 1985. Canon introduced Canon Electro-Optical System in 1987, named after the goddess of the dawn, EOS650 autofocus SLR camera is introduced. Also in 1987 the Canon Foundation was established, in 1988 Canon introduced Kyosei philosophy. The EOS1 Flagship Professional SLR line was launched in 1989, in the same year the EOS RT, the worlds first AF SLR with a fixed, semi-transparent pellicle mirror, was unveiled. In 1992 Canon launched the EOS5, the camera with eye-controlled AF. In 1995 Canon introduced the first commercially available SLR lens with image stabilization. EOS-1N RS, the worlds fastest AF SLR camera with a shooting speed of 10 frame/s at the time
32.
Canon EOS 450D
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The EOS 450D is a 12. 2-megapixel digital single-lens reflex camera that is part of the Canon EOS line of cameras. It is the successor to the EOS 400D/Digital Rebel XTi and it was announced on 23 January 2008 and released in March 2008 and April 2008 in North America. It was succeeded by the Canon EOS 500D which was announced on 25 March 2009, like its predecessors, it takes EF and EF-S lenses as well as a large selection of EOS system accessories
33.
Live preview
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Live preview is a feature that allows a digital cameras 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 preview image. The electronic screen can be either a liquid crystal display or an electronic viewfinder, the concept for cameras with live preview largely derives from electronic TV cameras. The first digital camera with an LCD for autogain framing live preview was the Casio QV-10 in 1995. The first DSLR to use live view for framing preview only, like other live view. The first interchangeable-lens DSLR to use a live preview for framing was the Fujifilm FinePix S3 Pro, the first general-use interchangeable-lens DSLR with live view for framing preview only like most fixed lens digicams was the Olympus E-330 of 2006. There are two modes of live-preview, with only a few manufacturers offering both in their digital cameras. This can be helpful when the lighting conditions are too dark for an optical viewfinder. This type of live preview is the live view type. This second type of live preview is the exposure simulation live preview type and this type of live preview eliminates reliance on traditional light metering usage. Many modern bridge and compact cameras with movie mode have only an automatic exposure and limited exposure compensation control, and live view that is primarily for framing only. Bridge cameras in general are higher-end, that is they contain more advanced features, better quality, larger size, and are more expensive than compacts. Mirrorless cameras feature a larger sensor and interchangeable lenses, like DSLRs, but sacrifice the SLR mirror mechanism and viewfinder to save size and cost, the SLT, developed by Sony, uses a mirror similar to that found in a DSLR. However, unlike the moving and fully reflective mirror of DSLRs and this gives a live real-time WYSIWYG exposure simulation preview in Full Manual / Manual ISO mode, and Auto-Exposure / Manual ISO modes, P, Tv, and Av. If Auto ISO is used, Autogain framing/focus live view suspends Exposure Simulation live view, later, Canon extended its more sophisticated DSLR ExpSim LV all shooting light conditions like its Powershot digicams. The most significant advances and difference in DSLR version of ES-LV was simulating exposure changes effects with chosen aperture changes without stopping down the aperture, the first interchangeable-lens DSLR to feature framing live preview was the 2004 Fujifilm FinePix S3 Pro. This is particularly the case since the advent of movie mode common to video features on these cameras
34.
DIGIC
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Digital Imaging Integrated Circuit is Canon Inc. s name for a family of signal processing and control units for digital cameras and camcorders. DIGIC units are used as image processors by Canon in its own digital imagery products, several generations of DIGICs exist, and are distinguished by a version number suffix. Over its numerous generations, DIGIC has evolved from a system involving a number of integrated circuits to a single chip system. Custom firmware for these units has developed to add features to the cameras. The original DIGIC was used on the PowerShot G3, Canon S1 IS, A520 and it consists of three separate chips, a video processing IC, an image processing IC and a camera control IC. DIGIC II is a chip system introduced in 2004, unlike the first DIGIC. DIGIC II also improved upon the original by adding a larger buffer and it has been used in some advanced consumer-level cameras and many discontinued digital SLRs such as Canon EOS 5D and Canon EOS 30D. DIGIC II uses high-speed DDR-SDRAM, which improves startup time and AF performance and it can write to memory card at speeds up to 5.8 MB/sec. Additionally, Canon claims DIGIC II improves color, sharpness, the DIGIC III Image Processor, introduced in 2006, was advertised to deliver improved image quality, faster operation and extended battery life compared to its predecessor. It also provides higher resolution for their LCD screens, additionally it has a 14-bit A to D converter providing greater bit depth than previous versions. It reverts to the AiAF system if the subject is not detected or not deemed to be a subject. The latter is useful at tourist spots where there may be many people around who are not intended to be the subject of the scene, ISAPS is a scene-recognition technology developed by Canon for digital cameras. Using an internal database of thousands of different photos, iSAPS also works with the DIGIC III Image Processor to improve speed and accuracy, as well as exposure. The Canon EOS-1D Mark III uses dual DIGIC III processors to achieve a rate of 10 frames per second at 10.1 MP. The Canon EOS-1Ds Mark III also uses dual DIGIC III processors to achieve a rate of five frames per second at 21.1 MP. It is also used in newer cameras in Canons PowerShot lines.264 1080p encoding, dual DIGIC4 processors are used in the EOS 7D and EOS-1D Mark IV. This CPU was introduced in 2014 to replace the DIGIC5 on mid-range compact cameras, particularly the Elph/IXUS, full specifications were not made available at introduction, but Canon claims a 60% speed bump over the original DIGIC4. In 2011, Canon introduced the DIGIC5, according to Canon, DIGIC5 analyses four times more image information to create each pixel, recording more detail and colour from a scene than ever before
35.
CompactFlash
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CompactFlash is a flash memory mass storage device used mainly in portable electronic devices. The format was specified and the devices were first manufactured by SanDisk in 1994, CompactFlash became the most successful of the early memory card formats, surpassing Miniature Card and SmartMedia. Subsequent formats, such as MMC/SD, various Memory Stick formats, most of these cards are smaller than CompactFlash while offering comparable capacity and speed. Proprietary memory card formats for use in audio and video, such as P2 and SxS, are faster. CompactFlash remains popular and is supported by many devices and high-end consumer devices. As of 2017, both Canon and Nikon use CompactFlash for their digital still cameras. Canon also chose CompactFlash as the medium for its professional high-definition tapeless video cameras. Ikegami professional video cameras can record video onto CompactFlash cards through an adaptor. Traditional CompactFlash cards use the Parallel ATA interface, but in 2008, CFast is based on the Serial ATA interface. In November 2010, SanDisk, Sony and Nikon presented a next generation card format to the CompactFlash Association, the new format has a similar form factor to CF/CFast but is based on the PCI Express interface instead of Parallel ATA or Serial ATA. The XQD card format was announced by the CompactFlash Association in December 2011. There are two subdivisions of CF cards,3.3 mm-thick type I and 5 mm-thick type II. The type II slot is used by miniature hard drives and some other devices, there are four main card speeds, original CF, CF High Speed, faster CF3.0 standard and the faster CF4.0 standard adopted as of 2007. CompactFlash was originally built around Intels NOR-based flash memory, but has switched to NAND technology, CF is among the oldest and most successful formats, and has held a niche in the professional camera market especially well. It has benefited from both a better cost to memory-size ratio and, for much of the life, generally greater available capacity than other formats. As some newer types are smaller, they can be used directly in a CF card slot with an adapter. Formats that can be used this way include SD/MMC, Memory Stick Duo, xD-Picture Card in a Type I slot and SmartMedia in a Type II slot, some multi-card readers use CF for I/O as well. The CompactFlash interface is a 50-pin subset of the 68-pin PCMCIA connector and it can be easily slipped into a passive 68-pin PCMCIA Type II to CF Type I adapter that fully meets PCMCIA electrical and mechanical interface specifications, according to compactflash. org
36.
Pixel
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The address of a pixel corresponds to its physical coordinates. LCD pixels are manufactured in a grid, and are often represented using dots or squares. Each pixel is a sample of an image, more samples typically provide more accurate representations of the original. The intensity of each pixel is variable, in color imaging systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black. The word pixel is based on a contraction of pix and el, the word pixel was first published in 1965 by Frederic C. Billingsley of JPL, to describe the elements of video images from space probes to the Moon. Billingsley had learned the word from Keith E. McFarland, at the Link Division of General Precision in Palo Alto, McFarland said simply it was in use at the time. The word is a combination of pix, for picture, the word pix appeared in Variety magazine headlines in 1932, as an abbreviation for the word pictures, in reference to movies. By 1938, pix was being used in reference to pictures by photojournalists. The concept of a picture element dates to the earliest days of television, some authors explain pixel as picture cell, as early as 1972. In graphics and in image and video processing, pel is often used instead of pixel, for example, IBM used it in their Technical Reference for the original PC. A pixel is generally thought of as the smallest single component of a digital image, however, the definition is highly context-sensitive. For example, there can be printed pixels in a page, or pixels carried by electronic signals, or represented by digital values, or pixels on a display device, or pixels in a digital camera. This list is not exhaustive and, depending on context, synonyms include pel, sample, byte, bit, dot, Pixels can be used as a unit of measure such as,2400 pixels per inch,640 pixels per line, or spaced 10 pixels apart. For example, a high-quality photographic image may be printed with 600 ppi on a 1200 dpi inkjet printer, even higher dpi numbers, such as the 4800 dpi quoted by printer manufacturers since 2002, do not mean much in terms of achievable resolution. The more pixels used to represent an image, the closer the result can resemble the original, the number of pixels in an image is sometimes called the resolution, though resolution has a more specific definition.3 megapixels. The pixels, or color samples, that form an image may or may not be in one-to-one correspondence with screen pixels. In computing, a composed of pixels is known as a bitmapped image or a raster image
37.
Active pixel sensor
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An active-pixel sensor is an image sensor consisting of an integrated circuit containing an array of pixel sensors, each pixel containing a photodetector and an active amplifier. Such an image sensor is produced using CMOS technology, and has emerged as an alternative to charge-coupled device image sensors. The term active pixel sensor was coined in 1985 by Tsutomu Nakamura who worked on the Charge Modulation Device active pixel sensor at Olympus, the MOS passive-pixel sensor used just a simple switch in the pixel to read out the photodiode integrated charge. Pixels were arrayed in a structure, with an access enable wire shared by pixels in the same row. At the end of each column was an amplifier, passive-pixel sensors suffered from many limitations, such as high noise, slow readout, and lack of scalability. The addition of an amplifier to each pixel addressed these problems, Noble in 1968 and Chamberlain in 1969 created sensor arrays with active MOS readout amplifiers per pixel, in essentially the modern three-transistor configuration. The CCD was invented in October 1969 at Bell Labs, a low-resolution mostly digital N-channel MOSFET imager with intra-pixel amplification, for an optical mouse application, was demonstrated in 1981. Another type of active pixel sensor is the infrared focal plane array designed to operate at cryogenic temperatures in the infrared spectrum. The exact date of origin of these devices is classified, by the late 1980s and early 1990s, the CMOS process was well established as a well controlled stable process and was the baseline process for almost all logic and microprocessors. Between 1993 and 1995, the Jet Propulsion Laboratory developed a number of prototype devices, though primitive, these devices demonstrated good image performance with high readout speed and low power consumption. In 1995, personnel from JPL founded Photobit Corp, many other small image sensor companies also sprang to life shortly thereafter due to the accessibility of the CMOS process and all quickly adopted the active pixel sensor approach. Most recent, the CMOS sensor technology has spread to medium-format photography with Phase One being the first to launch a medium format digital back with a Sony-built CMOS sensor, APS pixels solve the speed and scalability issues of the passive-pixel sensor. They generally consume less power than CCDs, have less image lag, unlike CCDs, APS sensors can combine the image sensor function and image processing functions within the same integrated circuit. APS sensors have found markets in many applications, especially camera phones. They have also used in other fields including digital radiography, military ultra high speed image acquisition, security cameras. Manufacturers include Aptina Imaging, Canon, Samsung, STMicroelectronics, Toshiba, OmniVision Technologies, Sony, cMOS-type APS sensors are typically suited to applications in which packaging, power management, and on-chip processing are important. CMOS type sensors are used, from high-end digital photography down to mobile-phone cameras. A big advantage of a CMOS sensor is that it is less expensive than a CCD sensor
38.
Image processor
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An image processor, image processing engine, also called media processor, is a specialized digital signal processor used for image processing in digital cameras, mobile phones or other devices. Image processors often employ parallel computing even with SIMD or MIMD technologies to increase speed, the digital image processing engine can perform a range of tasks. To increase the integration on embedded devices, often it is a system on a chip with multi-core processor architecture. The photodiodes employed in an image sensor are color-blind by nature, to get color into the picture, they are covered with different color filters, red, green and blue according to the pattern designated by the Bayer filter - named after its inventor. As each photodiode records the information for exactly one pixel of the image, without an image processor there would be a green pixel next to each red. This process, however, is complex and involves a number of different operations. Its quality depends largely on the effectiveness of the applied to the raw data coming from the sensor. The mathematically manipulated data becomes the photo file recorded, the image processor also assesses the whole picture to guess at the correct distribution of contrast. By adjusting the gamma value subtle tonal gradations, such as in skin or the blue of the sky. Noise is a found in any electronic circuitry. In digital photography its effect is visible as random spots of obviously wrong colour in an otherwise smoothly-coloured area. Noise increases with temperature and exposure times, when higher ISO settings are chosen the electronic signal in the image sensor is amplified, which at the same time increases the noise level, leading to a lower signal-to-noise ratio. The image processor attempts to separate the noise from the image information and this can be quite a challenge, as the image may contain areas with fine textures which, if treated as noise, may lose some of their definition. As the color and brightness values for each pixel are interpolated some image softening is applied to even out any fuzziness that has occurred, to preserve the impression of depth, clarity and fine details, the image processor must sharpen edges and contours. It therefore must detect edges correctly and reproduce them smoothly and without over-sharpening, some are known to be based on the Fujitsu Milbeaut, the Texas Instruments OMAP, Panasonic MN103, Zoran Coach, Altek Sunny or Sanyo image/video processors. ARM architecture processors with its NEON SIMD Media Processing Engines are often used in mobile phones, therefore, image processors must be optimised to cope with more data in the same or even a shorter period of time. Color image pipeline Image processing Digital image processing Digital image editing Demosaicing
39.
Canon EOS
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Canon EOS is an autofocus single-lens reflex camera camera series produced by Canon Inc. Introduced in 1987 with the Canon EOS650, all EOS cameras used 35 mm film until October 1996 when the EOS IX was released using the new, in 2000, the D30 was announced, as the first digital SLR designed and produced entirely by Canon. Since 2005, all newly announced EOS cameras have used digital image sensors rather than film, the EOS line is still in production as Canons current digital SLR range, and, with the 2012 introduction of the Canon EOS M, Canons mirrorless interchangeable-lens camera system. The name EOS was chosen for Eos, the Titan goddess of the dawn in Greek mythology and it competes primarily with the Nikon F series and its successors, as well as autofocus SLR systems from Olympus Corporation, Pentax, Sony/Minolta, and Panasonic/Leica. In 2010, Canon held 44. 5% market share in DSLRs, at the heart of the system is the EF lens mount, which replaced the previous FD lens mount, which mainly supported only manual-focus lenses. The bayonet-style EF lens mount is at the centre of the EOS camera system, breaking compatibility with the earlier FD mount, it was designed with no mechanical linkages between moving parts in the lens and in the camera. The aperture and focus are controlled via electrical contacts, with motors in the lens itself and this was similar in some ways to Canons earlier attempt at AF with the T80. Other manufacturers including Contax, Nikons 1983 F3AF and Olympus have since embraced this type of drive system. It is a lens mount compared to most of its competition. The flash system in the EOS cameras has gone through a number of evolutions since its first implementation, the basic EOS flash system was actually developed not for the first EOS camera, but rather for the last high-end FD-mount manual-focus camera, the T90, launched in 1986. This was the first Canon camera with through-the-lens flash metering, although other brands had been metering that way for some time and it also introduced the A-TTL system for better flash exposure in program mode, using infrared preflashes to gauge subject distance. This system was carried over into the early EOS cameras wholesale, A-TTL largely fell out of favor, and was replaced by E-TTL. This used a pre-flash for advanced metering, and used the system to judge where the main subject was for more accurate exposure. E-TTL II, which was an enhancement in the firmware only. Canon Speedlite-brand flashes have evolved alongside the cameras and they are capable of wired and wireless multi-flash setups, the latter using visible or infrared pulses to synchronise. Canon also produces Speedlite accessories, including the OC-E3 Off-Camera Shoe Cord, the Off-Camera Shoe Cord is popular among portrait photographers who need to have more control over lighting than a camera mounted flash can offer. As of 2017, Canon has released no fewer than 70 EOS SLR and DSLR camera models, in the 1990s, Canon worked with Kodak to produce digital camera bodies, starting with the EOS DCS3 in 1995. The first digital EOS SLR camera wholly designed and manufactured by Canon was the EOS D30, Canon sold two EOS cameras designed to use the APS film format, the EOS IX and the EOS IX Lite
40.
JPEG
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JPEG is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between size and image quality. JPEG typically achieves 10,1 compression with little loss in image quality. JPEG compression is used in a number of file formats. These format variations are not distinguished, and are simply called JPEG. The term JPEG is an initialism/acronym for the Joint Photographic Experts Group, the MIME media type for JPEG is image/jpeg, except in older Internet Explorer versions, which provides a MIME type of image/pjpeg when uploading JPEG images. JPEG files usually have an extension of. jpg or. jpeg. JPEG/JFIF supports a maximum size of 65, 535×65,535 pixels. JPEG stands for Joint Photographic Experts Group, the name of the committee created the JPEG standard. The Joint stood for ISO TC97 WG8 and CCITT SGVIII, in 1987 ISO TC97 became ISO/IEC JTC1 and in 1992 CCITT became ITU-T. Currently on the JTC1 side JPEG is one of two sub-groups of ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 1 – titled as Coding of still pictures, on the ITU-T side ITU-T SG16 is the respective body. The original JPEG group was organized in 1986, issuing the first JPEG standard in 1992, which was approved in September 1992 as ITU-T Recommendation T.81 and in 1994 as ISO/IEC 10918-1. The JPEG standard specifies the codec, which defines how an image is compressed into a stream of bytes and decompressed back into an image, the Exif and JFIF standards define the commonly used file formats for interchange of JPEG-compressed images. JPEG standards are formally named as Information technology – Digital compression, ISO/IEC10918 consists of the following parts, Ecma International TR/98 specifies the JPEG File Interchange Format, the first edition was published in June 2009. The JPEG compression algorithm is at its best on photographs and paintings of scenes with smooth variations of tone. For web usage, where the amount of used for an image is important. JPEG/Exif is also the most common format saved by digital cameras, on the other hand, JPEG may not be as well suited for line drawings and other textual or iconic graphics, where the sharp contrasts between adjacent pixels can cause noticeable artifacts. Such images may be saved in a lossless graphics format such as TIFF, GIF, PNG
41.
NTSC
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The first NTSC standard was developed in 1941 and had no provision for color. In 1953 a second NTSC standard was adopted, which allowed for television broadcasting which was compatible with the existing stock of black-and-white receivers. NTSC was the first widely adopted broadcast color system and remained dominant until 1997, North America, parts of Central America, and South Korea are adopting or have adopted the ATSC standards, while other countries are adopting or have adopted other standards instead of ATSC. After nearly 70 years, the majority of over-the-air NTSC transmissions in the United States ceased on January 1,2010, the majority of NTSC transmissions ended in Japan on July 24,2011, with the Japanese prefectures of Iwate, Miyagi, and Fukushima ending the next year. In March 1941, the committee issued a standard for black-and-white television that built upon a 1936 recommendation made by the Radio Manufacturers Association. Technical advancements of the side band technique allowed for the opportunity to increase the image resolution. The NTSC selected 525 scan lines as a compromise between RCAs 441-scan line standard and Philcos and DuMonts desire to increase the number of lines to between 605 and 800. The standard recommended a frame rate of 30 frames per second, other standards in the final recommendation were an aspect ratio of 4,3, and frequency modulation for the sound signal. In January 1950, the committee was reconstituted to standardize color television, in December 1953, it unanimously approved what is now called the NTSC color television standard. The compatible color standard retained full backward compatibility with existing black-and-white television sets, Color information was added to the black-and-white image by introducing a color subcarrier of precisely 315/88 MHz. These changes amounted to 0.1 percent and were tolerated by existing television receivers. The FCC had briefly approved a different color standard, starting in October 1950. However, this standard was incompatible with black-and-white broadcasts and it used a rotating color wheel, reduced the number of scan lines from 525 to 405, and increased the field rate from 60 to 144, but had an effective frame rate of only 24 frames per second. CBS rescinded its system in March 1953, and the FCC replaced it on December 17,1953, with the NTSC color standard, later that year, the improved TK-41 became the standard camera used throughout much of the 1960s. The NTSC standard has been adopted by countries, including most of the Americas. With the advent of television, analog broadcasts are being phased out. Most US NTSC broadcasters were required by the FCC to shut down their analog transmitters in 2009, low-power stations, Class A stations and translators were required to shut down by 2015. NTSC color encoding is used with the System M television signal, each frame is composed of two fields, each consisting of 262.5 scan lines, for a total of 525 scan lines
42.
PAL
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Phase Alternating Line is a colour encoding system for analogue television used in broadcast television systems in most countries broadcasting at 625-line /50 field per second. Other common colour encoding systems are NTSC and SECAM, all the countries using PAL are currently in process of conversion or have already converted standards to DVB, ISDB or DTMB. This page primarily discusses the PAL colour encoding system, the articles on broadcast television systems and analogue television further describe frame rates, image resolution and audio modulation. To overcome NTSCs shortcomings, alternative standards were devised, resulting in the development of the PAL, the goal was to provide a colour TV standard for the European picture frequency of 50 fields per second, and finding a way to eliminate the problems with NTSC. PAL was developed by Walter Bruch at Telefunken in Hannover, Germany, with important input from Dr. Kruse, the format was patented by Telefunken in 1962, citing Bruch as inventor, and unveiled to members of the European Broadcasting Union on 3 January 1963. When asked, why the system was named PAL and not Bruch the inventor answered that a Bruch system would not have sold very well. The first broadcasts began in the United Kingdom in June 1967, the one BBC channel initially using the broadcast standard was BBC2, which had been the first UK TV service to introduce 625-lines in 1964. Telefunken PALcolor 708T was the first PAL commercial TV set and it was followed by Loewe-Farbfernseher S920 & F900. Telefunken was later bought by the French electronics manufacturer Thomson, Thomson also bought the Compagnie Générale de Télévision where Henri de France developed SECAM, the first European Standard for colour television. The term PAL was often used informally and somewhat imprecisely to refer to the 625-line/50 Hz television system in general, accordingly, DVDs were labelled as PAL or NTSC even though technically the discs do not carry either PAL or NTSC composite signal. CCIR 625/50 and EIA 525/60 are the names for these standards, PAL. Both the PAL and the NTSC system use a quadrature amplitude modulated subcarrier carrying the chrominance information added to the video signal to form a composite video baseband signal. The frequency of this subcarrier is 4.43361875 MHz for PAL and NTSC4.43, the SECAM system, on the other hand, uses a frequency modulation scheme on its two line alternate colour subcarriers 4.25000 and 4.40625 MHz. Early PAL receivers relied on the eye to do that cancelling, however. The effect is that phase errors result in changes, which are less objectionable than the equivalent hue changes of NTSC. In any case, NTSC, PAL, and SECAM all have chrominance bandwidth reduced greatly compared to the luminance signal. The 4.43361875 MHz frequency of the carrier is a result of 283.75 colour clock cycles per line plus a 25 Hz offset to avoid interferences. Since the line frequency is 15625 Hz, the carrier frequency calculates as follows,4.43361875 MHz =283.75 ×15625 Hz +25 Hz
43.
Battery (electricity)
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An electric battery is a device consisting of one or more electrochemical cells with external connections provided to power electrical devices such as flashlights, smartphones, and electric cars. When a battery is supplying power, its positive terminal is the cathode. The terminal marked negative is the source of electrons that when connected to a circuit will flow. It is the movement of ions within the battery which allows current to flow out of the battery to perform work. Historically the term specifically referred to a device composed of multiple cells. Primary batteries are used once and discarded, the materials are irreversibly changed during discharge. Common examples are the battery used for flashlights and a multitude of portable electronic devices. Secondary batteries can be discharged and recharged multiple times using mains power from a wall socket, examples include the lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and smartphones. According to a 2005 estimate, the battery industry generates US$48 billion in sales each year. Batteries have much lower energy than common fuels such as gasoline. This is somewhat offset by the efficiency of electric motors in producing mechanical work. The usage of battery to describe a group of electrical devices dates to Benjamin Franklin, alessandro Volta built and described the first electrochemical battery, the voltaic pile, in 1800. This was a stack of copper and zinc plates, separated by brine-soaked paper disks, Volta did not understand that the voltage was due to chemical reactions. Although early batteries were of value for experimental purposes, in practice their voltages fluctuated. It consisted of a pot filled with a copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid. These wet cells used liquid electrolytes, which were prone to leakage and spillage if not handled correctly, many used glass jars to hold their components, which made them fragile and potentially dangerous. These characteristics made wet cells unsuitable for portable appliances, near the end of the nineteenth century, the invention of dry cell batteries, which replaced the liquid electrolyte with a paste, made portable electrical devices practical. Batteries convert chemical energy directly to electrical energy, a battery consists of some number of voltaic cells
44.
Digital camera
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A digital camera or digicam is a camera that produces digital images that can be stored in a computer, displayed on a screen and printed. Most cameras sold today are digital, and digital cameras are incorporated into many devices ranging from PDAs, Digital and movie cameras share an optical system, typically using a lens with a variable diaphragm to focus light onto an image pickup device. The diaphragm and shutter admit the correct amount of light to the imager, just as with film, however, unlike film cameras, digital cameras can display images on a screen immediately after being recorded, and store and delete images from memory. Many digital cameras can also record moving videos with sound, some digital cameras can crop and stitch pictures and perform other elementary image editing. The history of the camera began with Eugene F. Lally of the Jet Propulsion Laboratory. His 1961 idea was to take pictures of the planets and stars while travelling through space to give information about the astronauts position, unfortunately, as with Texas Instruments employee Willis Adcocks filmless camera in 1972, the technology had yet to catch up with the concept. Steven Sasson as an engineer at Eastman Kodak invented and built the first electronic camera using a charge-coupled device image sensor in 1975, earlier ones used a camera tube, later ones digitized the signal. Early uses were military and scientific, followed by medical. In the mid to late 1990s digital cameras became common among consumers, by the mid-2000s digital cameras had largely replaced film cameras, and higher-end cell phones had an integrated digital camera. By the beginning of the 2010s, almost all smartphones had a digital camera. The two major types of image sensor are CCD and CMOS. A CCD sensor has one amplifier for all the pixels, while each pixel in a CMOS active-pixel sensor has its own amplifier, compared to CCDs, CMOS sensors use less power. Cameras with a small sensor use a back-side-illuminated CMOS sensor, overall final image quality is more dependent on the image processing capability of the camera, than on sensor type. The resolution of a camera is often limited by the image sensor that turns light into that discrete signals. The brighter the image at a point on the sensor. Depending on the structure of the sensor, a color filter array may be used. The number of pixels in the sensor determines the cameras pixel count, in a typical sensor, the pixel count is the product of the number of rows and the number of columns. For example, a 1,000 by 1,000 pixel sensor would have 1,000,000 pixels, final quality of an image depends on all optical transformations in the chain of producing the image
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Full-frame
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The term full frame is used by users of digital single-lens reflex cameras as a shorthand for an image sensor format which is the same size as 35mm format film. Historically, 35mm was considered a film format compared with medium format, large format. This is in contrast to cameras with smaller sensors, much smaller than a full 35mm frame. Currently, the majority of 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 DCS100, Kodak states that 35mm film has the equivalent of 6,000 pixel horizontal resolution according to a Senior Vice President of IMAX. If the lens mounts are compatible, many lenses, including manual-focus models, when a lens designed for a full-frame camera, whether film or digital, is mounted on a DSLR with a smaller sensor size, only the center of the lens image circle is captured. The edges are cropped off, which is equivalent to zooming in on the section of the imaging area. When used with lenses designed for full frame film or digital cameras full-frame DSLRs offer a number of advantages compared to their smaller-sensor counterparts, one advantage is that wide-angle lenses designed for full-frame 35mm retain that same wide angle of view. On smaller-sensor DSLRs, wide-angle lenses have smaller angles of view equivalent to those of longer-focal-length lenses on 35mm film cameras. For example, a 24 mm lens on a camera with a factor of 1.5 has a 62° diagonal angle of view. On a full-frame digital camera, the 24 mm lens has the same 84° angle of view as it would on a 35mm film camera, equivalently, for the same DoF, the full-frame format will require a larger f-number. There are optical quality implications as well—not only because the image from the lens is effectively cropped—but because many lens designs are now optimized for sensors smaller than 36 mm ×24 mm. The full-frame sensor can also be useful with wide-angle perspective control or tilt/shift lenses, in particular, for example, a 200 mm lens on a camera with a crop factor of 1. 5× has the same angle of view as a 300 mm lens on a full-frame camera. The extra reach, for a number of pixels, can be helpful in specific areas of photography such as wildlife or sports. Lower size sensors also allow for the use of a range of lenses. By only using the center of the lens, these impurities are not noticed, in practice, this allows for the use of lower cost glass without corresponding loss of quality. Finally, full frame sensors allow for sensor designs that result in noise levels at high ISO. Pixel density is lower on full frame sensors and this means the pixels can be either spaced further apart from each other, or each photodiode can be manufactured at a slightly larger size
