1.
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
2.
Rotary disc shutter
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A rotary disc shutter is a type of shutter. It is notably used in motion picture cameras, rotary shutters are semicircular discs that spin in front of the film gate, alternately allowing light from the lens to strike the film, or blocking it. When blocking the light, the portion of the film is advanced. The spinning disc then exposes the new frame of film, the nature of light-sensitive film requires a shutter to block the light and prevent smearing of the image as the film is advanced through the camera. Digital sensors do not require a rotary shutter, although some digital cinema cameras do have them. On more advanced cameras the open portion of the shutter can be adjusted and this shutter setting is referred to as the shutter angle. Adjusting the shutter angle controls the proportion of time that the film is exposed to light during each frame interval, the angle of the shutter forms a proportion to the time that each frame of film is exposed, Shutter Angle 360 ∘ = Exposure Time Frame Interval. The primary reason that cinematographers adjust the angle is to control the amount of motion blur that is recorded on each successive frame of film. A tight shutter angle will constrict motion blur, a wide shutter angle will allow it. A 180° shutter angle is considered normal, so for instance, at 24 fps the frame Interval value is 0.04167 second. Using an exposure time of 1/50 second gives a shutter angle value of 173° and this is the reason for the rule-of-thumb Use an exposure time twice the value of the frames-per-second to get normal motion blur. Tight shutters create a stuttering stop-motion animation look that has become popular in action, in particular, tight shutters are used to capture particles flying through the air, such as dirt from an exploding mortar. On most film cameras the shutter angle is changed by removing the lens and this cannot be done while the camera is operating. Some cameras such as the Arriflex 435ES can modify their shutter angle during the shot and this is sometimes referred to as an electronic shutter. An electronic shutter can compensate for the change caused by a speed ramp without changing the aperture. Other types of shutter adjustments, such as an out-of-phase shutter, normally the film is held steady in the gate whenever it is exposed to light. Special shutter adjustments allow the film to be exposed while the mechanism is actually moving the film to the next frame. In the film Saving Private Ryan, cinematographer Janusz Kamiński used such an adjustment to give his film the look of World War II newsreel photography
3.
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
4.
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
5.
F-number
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The f-number of an optical system such as a camera lens is the ratio of the systems focal length to the diameter of the entrance pupil. It is a number that is a quantitative measure of lens speed. It is also known as the ratio, f-ratio, f-stop. The f-number is commonly indicated using a hooked f with the format f/N, the f-number N or f# is given by, N = f D where f is the focal length, and D is the diameter of the entrance pupil. It is customary to write f-numbers preceded by f/, which forms a mathematical expression of the pupil diameter in terms of f and N. Ignoring differences in light transmission efficiency, a lens with a greater f-number projects darker images, the brightness of the projected image relative to the brightness of the scene in the lenss field of view decreases with the square of the f-number. Doubling the f-number decreases the brightness by a factor of four. To maintain the same photographic exposure when doubling the f-number, the time would need to be four times as long. Most lenses have a diaphragm, which changes the size of the aperture stop. The entrance pupil diameter is not necessarily equal to the aperture stop diameter, a 100 mm focal length f/4 lens has an entrance pupil diameter of 25 mm. A200 mm focal length f/4 lens has a pupil diameter of 50 mm. The 200 mm lenss entrance pupil has four times the area of the 100 mm lenss entrance pupil, a T-stop is an f-number adjusted to account for light transmission efficiency. The word stop is sometimes confusing due to its multiple meanings, a stop can be a physical object, an opaque part of an optical system that blocks certain rays. In photography, stops are also a used to quantify ratios of light or exposure. The one-stop unit is known as the EV unit. On a camera, the setting is traditionally adjusted in discrete steps. Each stop is marked with its corresponding f-number, and represents a halving of the light intensity from the previous stop. This corresponds to a decrease of the pupil and aperture diameters by a factor of 1/2 or about 0.7071, each element in the sequence is one stop lower than the element to its left, and one stop higher than the element to its right
6.
Photography
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Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic sensor, this produces an electrical charge at each pixel. A negative image on film is used to photographically create a positive image on a paper base, known as a print. The word photography was created from the Greek roots φωτός, genitive of φῶς, light and γραφή representation by means of lines or drawing, several people may have coined the same new term from these roots independently. Johann von Maedler, a Berlin astronomer, is credited in a 1932 German history of photography as having used it in an article published on 25 February 1839 in the German newspaper Vossische Zeitung. Both of these claims are now widely reported but apparently neither has ever been confirmed as beyond reasonable doubt. Credit has traditionally given to Sir John Herschel both for coining the word and for introducing it to the public. Photography is the result of combining several technical discoveries, later Greek mathematicians Aristotle and Euclid also independently described a pinhole camera in the 5th and 4th centuries BCE. Daniele Barbaro described a diaphragm in 1566, wilhelm Homberg described how light darkened some chemicals in 1694. The fiction book Giphantie, published in 1760, by French author Tiphaigne de la Roche, the discovery of the camera obscura that provides an image of a scene dates back to ancient China. Leonardo da Vinci mentions natural camera obscura that are formed by dark caves on the edge of a sunlit valley, a hole in the cave wall will act as a pinhole camera and project a laterally reversed, upside down image on a piece of paper. So the birth of photography was primarily concerned with inventing means to capture, renaissance painters used the camera obscura which, in fact, gives the optical rendering in color that dominates Western Art. The camera obscura literally means dark chamber in Latin and it is a box with a hole in it which allows light to go through and create an image onto the piece of paper. Around the year 1800, British inventor Thomas Wedgwood made the first known attempt to capture the image in a camera obscura by means of a light-sensitive substance and he used paper or white leather treated with silver nitrate. The shadow images eventually darkened all over, the first permanent photoetching was an image produced in 1822 by the French inventor Nicéphore Niépce, but it was destroyed in a later attempt to make prints from it. Niépce was successful again in 1825, in 1826 or 1827, he made the View from the Window at Le Gras, the earliest surviving photograph from nature. Because Niépces camera photographs required a long exposure, he sought to greatly improve his bitumen process or replace it with one that was more practical. With an eye to eventual commercial exploitation, the partners opted for total secrecy, Daguerres efforts culminated in what would later be named the daguerreotype process
7.
Camera
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Thumb|A2016 Nikon D810 A camera is an optical instrument for recording or capturing images, which may be stored locally, transmitted to another location, or both. The images may be individual still photographs or sequences of images constituting videos or movies, the camera is a remote sensing device as it senses subjects without physical contact. The word camera comes from camera obscura, which means dark chamber and is the Latin name of the device for projecting an image of external reality onto a flat surface. The modern photographic camera evolved from the camera obscura, the functioning of the camera is very similar to the functioning of the human eye. A camera may work with the light of the spectrum or with other portions of the electromagnetic spectrum. A still camera is a device which creates a single image of an object or scene. All cameras use the basic design, light enters an enclosed box through a converging lens/convex lens. A shutter mechanism controls the length of time that light can enter the camera, a display, often a liquid crystal display, permits the user to view scene to be recorded and settings such as ISO speed, exposure, and shutter speed. A movie camera or a video camera operates similarly to a camera, except it records a series of static images in rapid succession. When the images are combined and displayed in order, the illusion of motion is achieved, the forerunner to the photographic camera was the camera obscura. The oldest known record of this principle is a description by Han Chinese philosopher Mozi, Mozi correctly asserted that the camera obscura image is inverted because light travels in straight lines from its source. In the 11th century Arab physicist Ibn al-Haytham s wrote very influential essays about experiments with light through an opening in a darkened room. The use of a lens in the opening of a wall or closed window shutter of a room to project images used as a drawing aid has been traced back to circa 1550. Since the late 17th century portable camera obscura devices in tents, before the development of the photographic camera, it had been known for hundreds of years that some substances, such as silver salts, darkened when exposed to sunlight. The first person to use this chemistry to create images was Thomas Wedgwood, to create images, Wedgwood placed items, such as leaves and insect wings, on ceramic pots coated with silver nitrate, and exposed the set-up to light. These images werent permanent, however, as Wedgwood didnt employ a fixing mechanism and he ultimately failed at his goal of using the process to create fixed images created by a camera obscura. The first permanent photograph of an image was made in 1826 by Joseph Nicéphore Niépce using a sliding wooden box camera made by Charles. Niépce had been experimenting with ways to fix the images of a camera obscura since 1816, the photograph Niépce succeeded in creating shows the view from his window
8.
Exposure value
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In photography, exposure value is a number that represents a combination of a cameras shutter speed and f-number, such that all combinations that yield the same exposure have the same EV. Exposure value is used to indicate an interval on the photographic exposure scale, with a difference of 1 EV corresponding to a standard power-of-2 exposure step. The EV concept was developed by the German shutter manufacturer Friedrich Deckel in the 1950s and its intent was to simplify choosing among equivalent camera exposure settings by replacing combinations of shutter speed and f-number with a single number. This was especially helpful to beginners with limited understanding of the shutter speed and aperture. The concept became known as the Light Value System in Europe, the proper EV was determined by the scene luminance and film speed, it was intended that the system also include adjustment for filters, exposure compensation, and other variables. With all of elements included, the camera would be set by transferring the single number thus determined. Exposure value has been indicated in various ways, although all camera settings with the same EV nominally give the same exposure, they do not necessarily give the same picture. The f-number determines the depth of field, and the shutter speed determines the amount of motion blur, if the EV is known, it can be used to select combinations of exposure time and f-number, as shown in Table 1. Greater exposure values are appropriate for photography in more brightly lit situations, to avoid confusion, some authors have used camera exposure to refer to combinations of camera settings. The 1964 ASA standard for automatic exposure controls for cameras, ASA PH2. 15-1964, took the same approach, common practice among photographers is nonetheless to use “exposure” to refer to camera settings as well as to photometric exposure. If, for example, the f-number is changed, an equivalent exposure time can be determined from t 2 t 1 = N22 N12. Performing this calculation mentally is tedious for most photographers, but the equation is solved with a calculator dial on an exposure meter or a similar dial on a standalone calculator. If the camera controls have detents, constant exposure can be maintained by counting the steps as one control is adjusted, the ratio t/N2 could be used to represent equivalent combinations of exposure time and f-number in a single value. But for many such combinations used in photography, the ratio gives a fractional value with a large denominator. For example, beginning with 1 s and f/1, decreasing exposure gives the simple sequence 0,1,2,3, the last two values shown frequently apply when using ISO100 speed imaging media in outdoor photography. Current cameras do not allow direct setting of EV, and cameras with automatic exposure control generally obviate the need for it, EV can nonetheless be helpful when used to transfer recommended exposure settings from an exposure meter to an exposure calculator. Used as an indicator of camera settings, EV corresponds to actual combinations of shutter speed, when the actual EV matches that recommended by the light level and the ISO speed, these settings should result in the “correct” exposure. If the common value of K =12.5 is used, at EV =15 the luminance is 380 cd/ft2 or 4096 cd/m2
9.
Mode dial
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A mode dial or camera dial is a dial used on digital cameras to change the cameras mode. Most digital cameras, including dSLR and SLR-like cameras, support modes, on point-and-shoot cameras which support modes a range of scene types is offered. On dSLR cameras and SLR-like cameras, mode dials usually offer access to manual settings, the more compact point-and-shoot cameras, and cameras offering a great many modes, do not have mode dials, using menus instead. Some SLR lenses themselves offer control over such as aperture. On most dSLRs and SLR-like bridge cameras, the dial is located at the top of the camera. On point-and-shoot cameras, however, the mode dials location is less standard, on many models, it is found on top like dSLRs. On other point-and-shoots, particularly those with a body, the dial is found on the back of the camera. Some thin cameras use a slide rather than a dial. Various camera types and specific cameras have different modes, the simpler dial in the top illustration has, Manual modes, Manual, Program, Shutter priority, Aperture priority. Automatic modes, Auto, Action, Portrait, Night portrait, Landscape, most dSLRs have a few manual settings and a small sample of automatic modes. Most SLR-like cameras have manual modes and several automatic scene modes, on point-and-shoot cameras, all manual control may be condensed into one mode or may be completely absent. Many compact cameras show a large array of scene modes, point-and-shoot and SLR-like digital cameras usually have a movie mode to capture videos, and many modern dSLRs also support movie modes. Detailed information found by users on the supported by digital cameras are to be found in the ongoing list of digital camera modes. Manual modes include, P, Program mode offers the photographer control over shutter speed. A or Av, Aperture priority AKA Aperture value allows the photographer to control the aperture, while the shutter speed, S or Tv, Shutter priority AKA Time value allows the photographer to control the shutter speed, while the aperture and ISO sensitivity are calculated by the camera. For example in portrait mode the camera would use an aperture to render the background out of focus. In the same conditions a smaller aperture would be used for a landscape. Some cameras have tens of modes, showing the majority only in the rather than on the dial
10.
Shutter priority
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Shutter priority refers to a setting on some cameras that allows the user to choose a specific shutter speed while the camera adjusts the aperture to ensure correct exposure. Shutter priority with longer exposures is chosen to create an impression of motion, for example, a waterfall will appear blurred and fuzzy. If the camera is panned with a subject, the background will appear blurred. When photographing sports or high-speed phenomena, shutter priority with short exposures can ensure that the motion is effectively frozen in the resulting image, like aperture priority, this mode allows for partial automation thus decreasing the need for total concentration. Shutter priority is often abbreviated as S or Tv on a mode dial. List of digital camera modes Aperture priority
11.
Light meter
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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
12.
Zone System
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The Zone System is a photographic technique for determining optimal film exposure and development, formulated by Ansel Adams and Fred Archer. The technique is based on the late 19th century sensitometry studies of Hurter, the Zone System provides photographers with a systematic method of precisely defining the relationship between the way they visualize the photographic subject and the final results. Although it originated with black-and-white sheet film, the Zone System is also applicable to roll film, an expressive image involves the arrangement and rendering of various scene elements according to the photographer’s desire. Achieving the desired image involves image management and control of image values, the Zone System is concerned with control of image values, ensuring that light and dark values are rendered as desired. Anticipation of the result before making the exposure is known as visualization. Any scene of photographic interest contains elements of different luminance, consequently, the exposure time is the same for all elements, but the image illuminance varies with the luminance of each subject element. Exposure is often determined using an exposure meter. The earliest meters measured overall average luminance, meter calibration was established to give satisfactory exposures for typical outdoor scenes, an averaging meter cannot distinguish between a subject of uniform luminance and one that consists of light and dark elements. When exposure is determined from average luminance measurements, the exposure of any given scene element depends on the relationship of its reflectance to the effective average reflectance. For example, an object of 4% reflectance would be given a different exposure in a scene of 20% effective average reflectance than it would be given in a scene of 12% reflectance. In a sunlit outdoor scene, the exposure for the object would also depend on whether the object was in sunlight or shade. Depending on the scene and the objective, any of the previous exposures might be acceptable. However, in situations, the photographer might wish to specifically control the rendering of the dark object, with overall average metering. When it is important to control the rendering of specific scene elements, even when metering individual scene elements, some adjustment of the indicated exposure is often needed if the metered scene element is to be rendered as visualized. Much has been written on the Zone System, but the concept is very simple—render light subjects as light, and dark subjects as dark, according to the photographer’s visualization. The Zone System assigns numbers from 0 through 10 to different brightness values, with 0 representing black,5 middle gray, and 10 pure white, to make zones easily distinguishable from other quantities, Adams and Archer used Roman rather than Arabic numerals. Strictly speaking, zones refer to exposure, with a Zone V exposure resulting in a rendering in the final image. Each zone differs from the preceding or following zone by a factor of two, so that a Zone I exposure is twice that of Zone 0, and so forth, a one-zone change is equal to one stop, corresponding to standard aperture and shutter controls on a camera
13.
Ansel Adams
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Ansel Easton Adams was an American photographer and environmentalist. His black and white photographs of the American West, especially Yosemite National Park, have been widely reproduced on calendars, posters, books. Adams and Fred Archer developed the Zone System as a way to determine proper exposure, the resulting clarity and depth characterized his photographs. He primarily used large-format cameras because their high resolution helped ensure sharpness in his images, Adams founded the photography group known as Group f/64, along with fellow photographers Willard Van Dyke and Edward Weston. Adams was born in the Western Addition of San Francisco, California and he was named after his uncle, Ansel Easton. His mothers family came from Baltimore, where his grandfather had a successful freight-hauling business but lost his wealth investing in failed mining. The Adams family came from New England, having migrated from Northern Ireland in the early 18th century and his paternal grandfather founded and built a prosperous lumber business which his father later ran, though his fathers natural talents lay more with sciences than with business. Later in life, Adams condemned that very same industry for cutting many of the great redwood forests. In 1907, his family moved 2 miles west to a new home near the Seacliff neighbourhood, the home had a splendid view of the Golden Gate and the Marin Headlands. San Francisco was devastated by the April 18,1906 San Francisco earthquake, the four year-old Ansel Adams was uninjured in the initial shaking but was tossed face-first into a garden wall during an aftershock three hours later, breaking and scarring his nose. Among his earliest memories was watching the smoke from the fire that destroyed much of the city a few miles to the east. A doctor recommended that his nose be reset once he reached maturity, Adams was a hyperactive child and prone to frequent sickness and hypochondria. He had few friends, but his home and surroundings on the heights facing the Golden Gate provided ample childhood activities. His father bought a telescope, and they enthusiastically shared the hobby of amateur astronomy. His father went on to serve as the paid secretary-treasurer of the Astronomical Society of the Pacific from 1925 to 1950, Ansels fathers business suffered great financial losses after the death of Ansels grandfather and the aftermath of the Panic of 1907. By 1912, the standard of living had dropped sharply. Ansel was dismissed from several schools for being restless and inattentive. Adams was then educated by tutors, his aunt Mary
14.
Frederick Scott Archer
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Frederick Scott Archer invented the photographic collodion process which preceded the modern gelatin emulsion. Scott Archer was the son of a butcher from Hertford who went to London to take an apprenticeship as a silversmith, later, he became a sculptor and found calotype photography useful as a way of capturing images of his sculptures. In publishing his discovery, he did so knowingly without first patenting it and he later developed the ambrotype jointly with Peter Wickens Fry. He died impoverished, as since he did not patent the process he made very little money from it. An obituary described him as a very inconspicuous gentleman, in poor health and his family received a gift of £747 after his death, raised by public subscription, and a small pension was also provided to support his three children after the death of their mother. The Royal Photographic Society has a collection of Scott Archers photographs, some are also held in the Victoria. Archer is buried at Kensal Green Cemetery in London, W10
15.
Black and white
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Black and white, often abbreviated B/W or B&W, and hyphenated black-and-white when used as an adjective, is any of several monochrome forms in visual arts. Black-and-white images are not usually starkly contrasted black and white and they combine black and white in a continuum producing a range of shades of gray. Even when most studios had the capability to make color films they were not heavily utilized as using the Technicolor process was expensive, for the years 1940–1966, a separate Academy Award for Best Art Direction was given for black-and-white movies along with one for color. Television, Television program was first transmitted in black-and-white, scottish inventor John Logie Baird demonstrated the worlds first color television transmission on July 3,1928 using a mechanical process. Some color broadcasts in the US began in the 1950s, with color becoming common in industrialized nations during the late 1960s. In the United States, the Federal Communications Commission settled on a color NTSC standard in 1953, color television became more widespread in the U. S. between 1963 and 1967, when the CBS and ABC networks joined NBC in broadcasting full color schedules. Canada began airing color television in 1966 while the United Kingdom began to use a different color system from July 1967 known as PAL. The Republic Of Ireland followed in 1970, in China, black and white television sets were the norm until as late as the 1990s, color TVs not outselling them until about 1989. While seldom used now, many consumer camcorders have the ability to record in black-and-white. Photography, Photographs were either black-and-white or shades of sepia, color photography was originally rare and expensive and again often containing inaccurate hues. Color photography became more common from the mid-20th century, Today, black-and-white is a niche market for photographers who use the medium for artistic purposes. This can take the form of film or digital conversion to grayscale. For amateur use certain companies such as Kodak manufactured black-and-white disposable cameras until 2009, also, certain films are produced today which give black-and-white images using the ubiquitous C41 color process. Printing press, Most American newspapers were black-and-white until the early 1980s, The New York Times, some claim that USA Today was the major impetus for the change to color. In the UK, color was only introduced from the mid-1980s. Even today, many newspapers restrict color photographs to the front, similarly, daily comic strips in newspapers were traditionally black-and-white with color reserved for Sunday strips. Sometimes color is reserved for the cover, magazines such as Jet magazine were either all or mostly black-and-white until the end of the 2000s when it became all-color. Manga are typically published in black-and-white although now it is part of its image, many school yearbooks are still entirely or mostly in black-and-white
16.
Negative (photography)
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In the case of color negatives, the colors are also reversed into their respective complementary colors. Typical color negatives have a dull orange tint due to an automatic color-masking feature that ultimately results in improved color reproduction. Negatives are normally used to make prints on photographic paper by projecting the negative onto the paper with a photographic enlarger or making a contact print. The paper is also darkened in proportion to its exposure to light, so a second reversal results which restores light, negatives were once commonly made on a thin sheet of glass rather than a plastic film, and some of the earliest negatives were made on paper. It is incorrect to call an image a negative solely because it is on a transparent material, transparent prints can be made by printing a negative onto special positive film, as is done to make traditional motion picture film prints for use in theaters. Some films used in cameras are designed to be developed by reversal processing, positives on film or glass are known as transparencies or diapositives, and if mounted in small frames designed for use in a slide projector or magnifying viewer they are commonly called slides. A positive image is a normal image, a negative image is a total inversion, in which light areas appear dark and vice versa. A negative color image is additionally color-reversed, with red areas appearing cyan, greens appearing magenta and blues appearing yellow, film negatives usually have less contrast, but a wider dynamic range, than the final printed positive images. The contrast typically increases when they are printed onto photographic paper, when negative film images are brought into the digital realm, their contrast may be adjusted at the time of scanning or, more usually, during subsequent post-processing. Film for cameras that use the 35 mm still format is sold as a strip of emulsion-coated and perforated plastic spooled in a light-tight cassette. Before each exposure, a mechanism inside the camera is used to pull an unexposed area of the out of the cassette. When all exposures have been made the strip is rewound into the cassette, after the film is chemically developed, the strip shows a series of small negative images. It is usually cut into sections for easier handling. Each of these images may be referred to as a negative. They are the images, from which all positive prints will derive. However, when an image is created from a negative image a positive image results. This makes most chemical-based photography a two-step process, which uses negative film, special films and development processes have been devised so that positive images can be created directly on the film, these are called positive, or slide, or reversal films and reversal processing. Scanning film negatives at the Wayback Machine NegaTIV -. -
17.
Reversal film
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In photography, reversal film is a type of photographic film that produces a positive image on a transparent base. The film is processed to produce transparencies or diapositives instead of negatives, Reversal film is produced in various sizes, from 35 mm roll film to 8×10 inch sheet film. A slide is a specially mounted individual transparency intended for projection onto a screen using a slide projector and this allows the photograph to be viewed by a large audience at once. The most common form is the 35 mm slide, with the image framed in a 2×2 inch cardboard or plastic mount. Reversal film is used as motion picture film, mostly in the 16 mm, Super 8 and 8 mm cine formats. This avoids the expense of using film, which requires additional film. The earliest practical and commercially successful color photography reversal process was the Lumière Autochrome and this was an additive method, using a panchromatic emulsion coated on a thin glass plate previously coated with a layer of dyed potato starch grains. Autochrome plates were discontinued in the 1930s after the introduction of Lumière Filmcolor in sheet film, also using the additive principle and reversal processing were the Agfa color screen plates and films and Dufaycolor film, all of which were discontinued by 1961. Leopold Godowsky, Jr. and Leopold Mannes, working with the Eastman Kodak Company, developed Kodachrome, Kodachrome was introduced in 1935 as 16mm motion picture film, and in 1936 as 35mm film for still cameras. The Kodachrome films contained no color dye couplers, these were added during processing, in late 1936, Agfacolor Neu was launched, Agfa having overcome earlier difficulties with color sensitivity problems. This film had the dye couplers incorporated into the emulsion, making processing simpler than for Kodachrome, amateurs who owned projection equipment used reversal films extensively because the cost of projection equipment and slide film was offset by not having to pay for prints. Eventually, print quality improved and prices decreased, and, by the 1970s, color negative film, digital media gradually replaced transparency film. All color reversal film sold today is developed with the E-6 process, the non-substantive Kodachrome films, the last of which was discontinued in 2009, were processed with the K-14 process. Polaroid produced an instant slide film called Polachrome and it was packaged in cassettes like normal 35mm film. A separate processing unit was used to develop it after exposure, black-and-white transparencies can be made directly with some modern black-and-white films, which normally yield negatives. The negative image is developed but not fixed, the remaining silver halide salts are re-exposed to light, developed and fixed, and the film is washed and dried. Black-and-white transparencies were once popular for presentation of materials using 3 1⁄4 by 4 glass-mounted slides. Such positive black-and-white projection is now rarely done, except in motion pictures, even where black-and-white positives are currently used, the process to create them typically uses an internegative with standard processing instead of a chemical reversal process
18.
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
19.
Minolta
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Minolta Co. Ltd. was a Japanese worldwide manufacturer of cameras, camera accessories, photocopiers, fax machines, and laser printers. Minolta was founded in Osaka, Japan, in 1928 as Nichi-Doku Shashinki Shōten and it is perhaps best known for making the first integrated autofocus 35mm SLR camera system. In 1931, the company adopted its current name, an acronym for Mechanism, Instruments, Optics, in 1933, the brand name first appeared on a camera, a copy of the Plaubel Makina simply called Minolta. In 2003, Minolta merged with Konica Corporation to form Konica Minolta,1928, Kazuo Tashima establishes Nichi-Doku Shashinki Shōten. 1929, Marketed the companys first camera, the Nifcarette,1937, The Minolta Flex is Japans second twin-lens reflex camera. 1947, Introduction of the long lived 35mm rangefinder camera Minolta-351958,1962, John Glenn takes a specially modified Ansco-logoed Minolta Hi-Matic camera into space aboard Friendship 7. The company changes its name to Minolta Camera Co. Ltd,1966, The Minolta SR-T101 SLR camera is one of the first with TTL full aperture light metering. The first is Topcon RE Super from 1963,1972, Minolta signs an agreement to cooperate with Leica in SLR development,1973, The Minolta CL is the first fruit of this agreement. 1976, The Leica R3 is introduced, Minolta produces the R3, R4, and R5 models in the Leica R series. Subsequent cameras are built in Germany by Leica themselves,1977, The Minolta XD-11 is introduced, the worlds first multi mode SLR offering M, A, S modes, with a Program override in S mode effected by a computer chip, the worlds first Program mode. 1981, Implementation of Minoltas invention and patent of TTL OTF exposure metering, the Minolta X-700 manual-focus SLR is introduced, this model is sold until 1999 and is enormously successful. The Minolta XD-11 is the first Minolta product branded with an updated logo,1985, The Minolta Maxxum 7000 Alpha Mount Camera becomes the worlds first autofocus 35mm SLR with in-camera autofocus motor. 1987, Honeywell files lawsuit against Minolta for patent infringement over autofocus technologies,1991, Minoltas autofocus design was found to infringe on the patents of Honeywell, a U. S. corporation. 1994, The company changes its name to Minolta Co. Ltd. because it no longer is primarily a camera company,1995, Introduction of the Minolta RD-175, a 1. 75-megapixel digital SLR camera. 1996, The Minolta Vectis camera is a completely new SLR system designed around the Advanced Photo System film format,1998, The Minolta Maxxum 9 autofocus SLR is introduced. This system is targeted toward the photographer and has many features not duplicated by the competition. 2003, DiMAGE A1 introduced worlds first sensor-based anti-shake, and was the final Minolta product branded prior to the Konica Minolta merger,2004, Minolta and Konica officially merge to become Konica Minolta Holdings, Inc. 2005, The company announces joint venture with Sony on CCD,2006, Konica Minolta announces it is discontinuing all film and digital camera production, ending a 78-year history as a camera manufacturer
20.
Minolta Maxxum 7000
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The Minolta MAXXUM7000 35mm SLR camera was introduced in February 1985. It was the first camera to feature both integrated autofocus and motorised film advance, the configuration for later amateur and professional single lens reflex cameras. Although the Nikon F3AF, Pentax ME F and Chinon CE-5 already had presented autofocus single lens reflex cameras, the Pentax ME F had focus sensors in the camera body, while the Chinon CE-5 used a lens with built-in active infrared sensors. Nikon already had a camera with integrated motor drive on the market, the N2000, but its autofocus counterpart, the Minolta 7000 had its AF sensors and the focusing drive inside the camera body, and as a result the lenses could be much smaller and cheaper. The aperture and focus were mechanically driven through the mount from the camera body. However, electronically controlled buttons on the body now replaced the mechanical aperture ring on the lens. The metal housing of older Minolta SLR cameras was replaced with a lighter, cheaper body made of plastics. In other respects, the Maxxum offered most of the features of other cameras of the day, with the exception of a rather low flash sync speed. Minolta introduced a new mount, the A system, breaking compatibility with its earlier manual-focus lenses in the MC. Konica and Minolta merged their photo and camera businesses in October 2003, when Pentax and Nikon entered the autofocus segment, both used a similar passive array AF system as Minolta, but retained compatibility with their existing manual-focus K and F mounts respectively. Canon, like Minolta, chose to change its mount completely, introducing the EOS 600-series a few later, breaking compatibility with the former FL. Early Maxxum 7000 cameras were inscribed MAXXUM7000 with a crossed XX, the oil giant Exxon considered this to be a violation of its trademark, because the XX in its logo was linked in a similar fashion. As a result, Minolta was allowed to distribute cameras that were already produced, all Maxxum cameras produced thereafter had a regularly scripted double X. Minoltas autofocus design was found to infringe the patents of Honeywell, a U. S. corporation. After protracted litigation, Minolta in 1991 was ordered to pay Honeywell damages, penalties, trial costs and other expenses in a final amount of $127.6 million
21.
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
22.
Aperture
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In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of a system determine the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, a wide aperture admits uncollimated rays, resulting in a sharp focus only for rays coming from a certain distance. This means that a wide aperture results in an image that is sharp for things at the correct distance, the aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane. In the human eye, the pupil is the aperture, an optical system typically has many openings or structures that limit the ray bundles. In general, these structures are called stops, and the stop is the stop that primarily determines the ray cone angle. In some contexts, especially in photography and astronomy, aperture refers to the diameter of the aperture stop rather than the stop or the opening itself. For example, in a telescope, the stop is typically the edges of the objective lens or mirror. One then speaks of a telescope as having, for example, note that the aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a large stop to be the aperture stop for the system. In astrophotography, the aperture may be given as a measure or as the dimensionless ratio between that measure and the focal length. In other photography, it is given as a ratio. Sometimes stops and diaphragms are called apertures, even when they are not the stop of the system. The word aperture is used in other contexts to indicate a system which blocks off light outside a certain region. In astronomy, for example, a photometric aperture around a star usually corresponds to a window around the image of a star within which the light intensity is assumed. The aperture stop is an important element in most optical designs and its most obvious feature is that it limits the amount of light that can reach the image/film plane. This can be unavoidable, as in a telescope where one wants to collect as much light as possible, or deliberate
23.
Nikon
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Nikon Corporation, also known just as Nikon, is a Japanese multinational corporation headquartered in Tokyo, Japan, specializing in optics and imaging products. The companies held by Nikon form the Nikon Group, Nikons main competitors in camera and lens manufacturing include Canon, Sony, Fujifilm, Panasonic, Pentax, and Olympus. Founded on July 25,1917 as Nippon Kōgaku Kōgyō Kabushikigaisha, Nikon is a member of the Mitsubishi group of companies. Nikon Corporation was established on 25 July 1917 when three leading optical manufacturers merged to form a comprehensive, fully integrated optical company known as Nippon Kōgaku Tōkyō K. K. Over the next sixty years, this company became a manufacturer of optical lenses and equipment used in cameras, binoculars, microscopes. During World War II the company operated thirty factories with 2,000 employees, manufacturing binoculars, lenses, bomb sights, after the war Nippon Kōgaku reverted to producing its civilian product range in a single factory. In 1948, the first Nikon-branded camera was released, the Nikon I, Nikon lenses were popularised by the American photojournalist David Douglas Duncan. Duncan was working in Tokyo when the Korean War began, Duncan had met a young Japanese photographer, Jun Miki, who introduced Duncan to Nikon lenses. From July 1950 to January 1951, Duncan covered the Korean War, fitting Nikon optics to his Leica rangefinder cameras produced high contrast negatives with very sharp resolution at the centre field. Founded in 1917 as Nippon Kōgaku Kōgyō Kabushikigaisha, the company was renamed Nikon Corporation, after its cameras, the name Nikon, which dates from 1946, is a merging of Nippon Kōgaku and Zeisss brand Ikon. This would cause some problems in Germany as Zeiss complained that Nikon violated its trademarked camera. From 1963 to 1968 the Nikon F in particular was therefore labeled Nikkor, the Nikkor brand was introduced in 1932, a westernised rendering of an earlier version Nikkō, an abbreviation of the companys original full name. Nikkor is the Nikon brand name for its lenses, another early brand used on microscopes was Joico, an abbreviation of Japan Optical Industries Co. Expeed is the brand Nikon uses for its processors since 2007. The Nikon SP and other 1950s and 1960s rangefinder cameras competed directly with models from Leica, however, the company quickly ceased developing its rangefinder line to focus its efforts on the Nikon F single-lens reflex line of cameras, which was successful upon its introduction in 1959. For nearly 30 years, Nikons F-series SLRs were the most widely used small-format cameras among professional photographers, however, as autofocus SLRs became available from Minolta and others in the mid-1980s, Nikons line of manual-focus cameras began to seem out of date. Canon introduced a new type of lens-camera interface with its entirely electronic Canon EOS cameras, the much faster lens performance permitted by Canons electronic focusing and aperture control prompted many professional photographers to switch to the Canon system through the 1990s. Nikon created some of the first digital SLRs for NASA, used in the Space Shuttle since 1991, after a 1990s partnership with Kodak to produce digital SLR cameras based on existing Nikon film bodies, Nikon released the Nikon D1 SLR under its own name in 1999
24.
Nikon F5
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The Nikon F5 is a 35 mm film-based single-lens reflex camera body manufactured by Nikon from 1996 through 2004. It was the fifth in Nikons professional film camera line, which began in 1959 with the Nikon F and it followed the Nikon F4 of 1988, which had introduced in-body autofocus to Nikons professional line. The F5 was in turn succeeded by the Nikon F6, as well as Nikons parallel range of professional digital SLRs, important advances in the F5 included, Nikon 3-D color matrix meter. A mirror-balance system that reduced camera shake, electronically controlled exposure times from 1/8000 second to 30 seconds. Built-in 8 frame per second motor drive, however, at 1/300 second, flash units could not use their full capacity. Full support for Nikkor AF-S and G designated lenses, support for the Vibration Reduction image stabilization feature of newer Nikkor lenses. Five focus points for the sensor with intelligent dynamic autofocus mode. A new industrial design by Giorgetto Giugiaro, an integral vertical/battery grip with additional shutter release and adjustment wheel controls. In common with the F3 and F4 it relied upon battery power in order to function, variants, Nikon introduced a very limited production anniversary edition of the F5 to celebrate 50 years of Nippon Kogaku. It featured a colored top plate, grey handgrip and a special DP-30 metering prism with its historic Nikon font. On the reverse is found the original Nippon Kogaku trademark logo, approximately 3000 were made for the global market. They were quickly snatched up around the world by collectors who saw the F5 as the last of the professional grade film SLRs by Nikon. It was discontinued in 2004 as it was facing competition from its competitors. During the late 1990s, Nikon and Kodak collaborated on a range of professional digital SLRs which combined Nikon bodies with Kodak digital sensors and electronics. The initial range was based around the semi-professional Nikon F90, but the later Kodak DCS600, on a physical level they consisted of a Nikon F5 with the film transport equipment replaced with a custom-made Kodak digital back. The digital back extended beneath the camera to house the battery, the Kodak DCS600 series was launched in 1999, and initially consisted of the 2 megapixel Kodak DCS620 and the 6 megapixel DCS660, which had an initial launch price of $29,995. Kodak replaced the 600 series with the upgraded DCS700 series in 2001, which consisted of the high-sensitivity DCS 720x, by 2001 Kodak faced competition from the popular Nikon D1 and Nikon D1x, which were physically smaller and cheaper. The DCS 760s initial list price was $8,000, media related to Nikon F5 at Wikimedia Commons Debut of the Nikon F5, by Nikon Comprehensive Nikon F5 site
25.
Nikon F6
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The Nikon F6 is designed by Nikon and manufactured at their Sendai Plant. The F6 is the current model of Nikons F series and it is still in production and it replaces the Nikon F5, manufactured from 1996 to 2004. The Nikon F6 accepts nearly any Nikon F-mount lens with full metering functionality, focusing screen, B-type BriteView Clear Matte Screen II, interchangeable with six other optional focusing screens Viewfinder frame coverage, Approx. 0. 74x with 50mm lens set to infinity at -1. 0m-1 Autofocus, TTL phase detection, Nikon Multi-CAM2000 autofocus module Autofocus detection range, die-cast camera chassis, rear and film cover made of aluminium alloy The front, top and bottom covers are made of magnesium alloy. Parts made out of use the thixomold process. Remote shutter release, 10-pin terminal Power source,2 x CR123A, or with optional MB-40 battery pack,8 x AA or 1 x EN-EL4 The F6 has been engineered for reduced noise and it includes a feature called Silent that allows for quieter single frame advance. User feedback resulted in improved ergonomics for the Nikon D2 family from which the F6s ergonomics is derived and these include redesigned tilted control wheels, shutter button and larger buttons. The F6 deviates from the F5 integrated system with a vertical grip housing. 11-zone autofocus, with 9 cross-type sensors, the viewfinder has a 37-segment vertical metering scale. Integrated date/time/exposure information film imprint and intervalometer, with the Nikon MV-1 data reader accessory, the ability to write exposure and lens data to a flash memory card, so photographers need not write that information down. While this accessory was introduced at the time as the F6, it is also compatible with the F5. The F6 is designed for reliability and durability like previous Nikon F-series cameras, the camera also has a manual film rewind, 100% coverage viewfinder and low 37ms shutter lag. The F6 is also Nikons first F-series camera without an interchangeable viewfinder pentaprism, the F6 uses the same Multi-CAM2000 autofocus module as the D2X professional-level digital SLR, which is a DX camera. The F6 is a 135 film camera and since the same AF sensor unit is used in cameras, the AF sensors cover a smaller area of the F6s frame relative to the coverage on the D2X. Media related to Nikon F6 at Wikimedia Commons Nikon F6 from the Nikon Digital Archives
26.
Sony Alpha 900
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The α900 is a full-frame digital SLR camera, produced by Sony. An early design study of the camera was shown at PMA on 8 March 2007, Sony officially introduced the final camera on 9 September 2008 prior to photokina 2008. In October 2011, Sony Japan announced the end of production. It does not have video/movie recording and this mode, first introduced on the DSLR-A900, allows the photographer to take a sample image at the current settings. When this mode is enabled in the settings, then using the depth of field preview button makes an image of the subject. The display shows the image and its image histogram, but it is not stored on the memory card, at that point, the photographer can accept current settings or simulate how the image would look with changes in aperture, shutter speed, dynamic range optimizer and white balance. If the photographer prefers those new settings he simply continues to work to accept them, otherwise he can reject them by depressing the garbage can icon. He can also compare the sample to the simulation by depressing the DISP button, the DSLR-A900 requires a labour-intensive alignment procedure in the factory in order to provide a 100% scene view in the viewfinder
27.
Wayback Machine
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The Internet Archive launched the Wayback Machine in October 2001. It was set up by Brewster Kahle and Bruce Gilliat, and is maintained with content from Alexa Internet, the service enables users to see archived versions of web pages across time, which the archive calls a three dimensional index. Since 1996, the Wayback Machine has been archiving cached pages of websites onto its large cluster of Linux nodes and it revisits sites every few weeks or months and archives a new version. Sites can also be captured on the fly by visitors who enter the sites URL into a search box, the intent is to capture and archive content that otherwise would be lost whenever a site is changed or closed down. The overall vision of the machines creators is to archive the entire Internet, the name Wayback Machine was chosen as a reference to the WABAC machine, a time-traveling device used by the characters Mr. Peabody and Sherman in The Rocky and Bullwinkle Show, an animated cartoon. These crawlers also respect the robots exclusion standard for websites whose owners opt for them not to appear in search results or be cached, to overcome inconsistencies in partially cached websites, Archive-It. Information had been kept on digital tape for five years, with Kahle occasionally allowing researchers, when the archive reached its fifth anniversary, it was unveiled and opened to the public in a ceremony at the University of California, Berkeley. Snapshots usually become more than six months after they are archived or, in some cases, even later. The frequency of snapshots is variable, so not all tracked website updates are recorded, Sometimes there are intervals of several weeks or years between snapshots. After August 2008 sites had to be listed on the Open Directory in order to be included. As of 2009, the Wayback Machine contained approximately three petabytes of data and was growing at a rate of 100 terabytes each month, the growth rate reported in 2003 was 12 terabytes/month, the data is stored on PetaBox rack systems manufactured by Capricorn Technologies. In 2009, the Internet Archive migrated its customized storage architecture to Sun Open Storage, in 2011 a new, improved version of the Wayback Machine, with an updated interface and fresher index of archived content, was made available for public testing. The index driving the classic Wayback Machine only has a bit of material past 2008. In January 2013, the company announced a ground-breaking milestone of 240 billion URLs, in October 2013, the company announced the Save a Page feature which allows any Internet user to archive the contents of a URL. This became a threat of abuse by the service for hosting malicious binaries, as of December 2014, the Wayback Machine contained almost nine petabytes of data and was growing at a rate of about 20 terabytes each week. Between October 2013 and March 2015 the websites global Alexa rank changed from 162 to 208, in a 2009 case, Netbula, LLC v. Chordiant Software Inc. defendant Chordiant filed a motion to compel Netbula to disable the robots. Netbula objected to the motion on the ground that defendants were asking to alter Netbulas website, in an October 2004 case, Telewizja Polska USA, Inc. v. Echostar Satellite, No.02 C3293,65 Fed. 673, a litigant attempted to use the Wayback Machine archives as a source of admissible evidence, Telewizja Polska is the provider of TVP Polonia and EchoStar operates the Dish Network
28.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
29.
35 mm equivalent focal length
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In photography, the 35 mm equivalent focal length is a measure that indicates the angle of view of a particular combination of a camera lens and film or sensor size. The term is useful because most photographers experienced with interchangeable lenses are most familiar with the 35 mm film format, on any 35 mm film camera, a 28 mm lens is a wide-angle lens, and a 200 mm lens is a long-focus lens. The 35 mm equivalent focal length of a particular combination is the focal length that one would need for a 35 mm film camera to obtain the same angle of view. Most commonly, the 35 mm equivalent focal length is based on equal diagonal angle of view and this definition also in the CIPA guideline DCG-001. Alternatively, it may sometimes be based on angle of view. 35 mm equivalent focal lengths are calculated by multiplying the focal length of the lens by the crop factor of the sensor. Quoted 35 mm equivalent focal lengths typically ignore depth of field, the perceived DOF of smaller sensors is deeper due to the shorter focal length lenses. Equivalent depth of field can be calculated the same way using the crop factor, a standard 35 mm film image is 36 mm wide by 24 mm tall, and the diagonal is 43.3 mm. This is because these sensor size specifications refer to the size of a camera tube, tubes are not used on digital cameras, but the same specifications are used. Apart from the width- and diagonal-based 35 mm equivalent focal length definitions, there is a definition, EFL =50 f /d mm. However. Focal Length Conversion for medium format and large format, at photo. net Focal Length at dpreview
30.
Angle of view
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In photography, angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the general term field of view. It is important to distinguish the angle of view from the angle of coverage, typically the image circle produced by a lens is large enough to cover the film or sensor completely, possibly including some vignetting toward the edge. A cameras angle of view not only on the lens. Digital sensors are usually smaller than 35mm film, and this causes the lens to have an angle of view than with 35mm film. In everyday digital cameras, the factor can range from around 1, to 1.6. For lenses projecting rectilinear images of distant objects, the focal length. Calculations for lenses producing non-rectilinear images are more complex and in the end not very useful in most practical applications. Angle of view may be measured horizontally, vertically, or diagonally, for example, for 35mm film which is 36 mm wide and 24mm high, d =36 mm would be used to obtain the horizontal angle of view and d =24 mm for the vertical angle. Because this is a function, the angle of view does not vary quite linearly with the reciprocal of the focal length. However, except for wide-angle lenses, it is reasonable to approximate α ≈ d f radians or 180 d π f degrees. The effective focal length is equal to the stated focal length of the lens. Angle of view can also be determined using FOV tables or paper or software lens calculators, consider a 35 mm camera with a lens having a focal length of F =50 mm. The dimensions of the 35 mm image format are 24 mm ×36 mm, here α is defined to be the angle-of-view, since it is the angle enclosing the largest object whose image can fit on the film. We want to find the relationship between, the angle α the opposite side of the triangle, d /2 the adjacent side, S2 Using basic trigonometry, we find. For macro photography, we neglect the difference between S2 and F. From the thin lens formula,1 F =1 S1 +1 S2, a second effect which comes into play in macro photography is lens asymmetry. The lens asymmetry causes an offset between the plane and pupil positions
31.
Chromatic aberration
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In optics, chromatic aberration is an effect resulting from dispersion in which there is a failure of a lens to focus all colors to the same convergence point. It occurs because lenses have different refractive indices for different wavelengths of light, the refractive index of transparent materials decreases with increasing wavelength in degrees unique to each. Since the focal length f of a lens is dependent on the index n. There are two types of aberration, axial, and transverse. Axial aberration occurs when different wavelengths of light are focused at different distances from the lens, transverse aberration occurs when different wavelengths are focused at different positions in the focal plane. The acronym LCA is used, but ambiguous, and may refer to either longitudinal or lateral CA, for clarity and these two types have different characteristics, and may occur together. Axial CA occurs throughout the image and is specified by optical engineers, optometrists, and vision scientists in the unit of focus known widely as diopters, transverse CA does not occur in the center, and increases towards the edge, but is not affected by stopping down. In the earliest uses of lenses, chromatic aberration was reduced by increasing the length of the lens where possible. For example, this could result in extremely long telescopes such as the very long aerial telescopes of the 17th century, isaac Newtons theories about white light being composed of a spectrum of colors led him to the conclusion that uneven refraction of light caused chromatic aberration. There exists a point called the circle of least confusion, where chromatic aberration can be minimized and it can be further minimized by using an achromatic lens or achromat, in which materials with differing dispersion are assembled together to form a compound lens. The most common type is a doublet, with elements made of crown. This reduces the amount of chromatic aberration over a range of wavelengths. By combining more than two lenses of different composition, the degree of correction can be increased, as seen in an apochromatic lens or apochromat. Similarly, the benefit of apochromats is not simply that they focus 3 wavelengths sharply, many types of glass have been developed to reduce chromatic aberration. These are low dispersion glass, most notably, glasses containing fluorite and these hybridized glasses have a very low level of optical dispersion, only two compiled lenses made of these substances can yield a high level of correction. The use of achromats was an important step in the development of the optical microscope, an alternative to achromatic doublets is the use of diffractive optical elements. Diffractive optical elements are able to generate arbitrary complex wave fronts from a sample of material which is essentially flat. Diffractive optical elements have negative characteristics, complementary to the positive Abbe numbers of optical glasses
32.
Circle of confusion
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In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, in photography, the circle of confusion is used to determine the depth of field, the part of an image that is acceptably sharp. A standard value of CoC is often associated with image format, but the most appropriate value depends on visual acuity, viewing conditions. Usages in context include maximum permissible circle of confusion, circle of confusion diameter limit, real lenses do not focus all rays perfectly, so that even at best focus, a point is imaged as a spot rather than a point. The smallest such spot that a lens can produce is often referred to as the circle of least confusion, two important uses of this term and concept need to be distinguished, For describing the largest blur spot that is indistinguishable from a point. A lens can precisely focus objects at one distance, objects at other distances are defocused. Defocused object points are imaged as blur spots rather than points, the greater the distance an object is from the plane of focus, such a blur spot has the same shape as the lens aperture, but for simplicity, is usually treated as if it were circular. In practice, objects at different distances from the camera can still appear sharp. The common criterion for “acceptable sharpness” in the image is that the blur spot be indistinguishable from a point. For describing the blur spot achieved by a lens, at its best focus or more generally, the term circle of confusion is applied more generally, to the size of the out-of-focus spot to which a lens images an object point. In idealized ray optics, where rays are assumed to converge to a point when perfectly focused, a more general blur spot has soft edges due to diffraction and aberrations, and may be non-circular due to the aperture shape. Therefore, the concept needs to be carefully defined in order to be meaningful. Suitable definitions often use the concept of encircled energy, the fraction of the optical energy of the spot that is within the specified diameter. Values of the fraction vary with application, in photography, the circle of confusion diameter limit for the final image is often defined as the largest blur spot that will still be perceived by the human eye as a point. Conventions in terms of the measure are also commonly used. The DoF computed using these conventions will need to be adjusted if the image is cropped before enlarging to the final image size, or if the size. Using the “Zeiss formula”, the circle of confusion is sometimes calculated as d/1730 where d is the measure of the original image. For full-frame 35 mm format this comes out to be 0.025 mm, a more widely used CoC is d/1500, or 0.029 mm for full-frame 35 mm format, which corresponds to resolving 5 lines per millimeter on a print of 30 cm diagonal
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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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Color temperature
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The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of comparable color to that of the light source. Color temperature is a characteristic of light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, horticulture. Color temperature is conventionally expressed in kelvins, using the symbol K, Color temperatures over 5000 K are called cool colors, while lower color temperatures are called warm colors. The fact that warm lighting in this sense actually has a color temperature often leads to confusion. The color temperature of the radiation emitted from an ideal black body is defined as its surface temperature in kelvins. This permits the definition of a standard by which light sources are compared, to the extent that a hot surface emits thermal radiation but is not an ideal black-body radiator, the color temperature of the light is not the actual temperature of the surface. An incandescent lamps light is thermal radiation, and the bulb approximates an ideal black-body radiator and this means that the emitted radiation does not follow the form of a black-body spectrum. These sources are assigned what is known as a color temperature. CCT is the temperature of a black-body radiator which to human color perception most closely matches the light from the lamp. Because such an approximation is not required for incandescent light, the CCT for an incandescent light is simply its unadjusted temperature, the Sun closely approximates a black-body radiator. The effective temperature, defined by the radiative power per square unit, is about 5780 K. The color temperature of sunlight above the atmosphere is about 5900 K, as the Sun crosses the sky, it may appear to be red, orange, yellow or white depending on its position. The changing color of the Sun over the course of the day is mainly a result of scattering of light and is not due to changes in black-body radiation. The blue color of the sky is caused by Rayleigh scattering of the sunlight from the atmosphere, some early morning and evening light has a lower color temperature due to increased low-wavelength light scattering by the Tyndall effect. Daylight has a similar to that of a black body with a correlated color temperature of 6500 K or 5500 K. For colors based on theory, blue occurs at higher temperatures. This is the opposite of the cultural associations attributed to colors, in red is hot. For lighting building interiors, it is important to take into account the color temperature of illumination
35.
Depth of field
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In some cases, it may be desirable to have the entire image sharp, and a large DOF is appropriate. In other cases, a small DOF may be more effective, in cinematography, a large DOF is often called deep focus, and a small DOF is often called shallow focus. Precise focus is possible at one distance, at that distance. At any other distance, a point object is defocused, and will produce a blur spot shaped like the aperture, when this circular spot is sufficiently small, it is indistinguishable from a point, and appears to be in focus, it is rendered as acceptably sharp. The acceptable circle of confusion is influenced by visual acuity, viewing conditions, the increase of the circle diameter with defocus is gradual, so the limits of depth of field are not hard boundaries between sharp and unsharp. For 35 mm motion pictures, the area on the film is roughly 22 mm by 16 mm. The limit of tolerable error was traditionally set at 0.05 mm diameter, while for 16 mm film, where the size is half as large. More modern practice for 35 mm productions set the circle of confusion limit at 0.025 mm, for full-frame 35mm still photography, the circle of confusion is usually chosen to be about 1/30 mm. Many sources propose CoC limits as a fraction of the film format diagonal, the three formats above at fraction 1/1500 would use 0.029,0.056, and 0.017 mm. Traditional depth-of-field formulas and tables assume equal circles of confusion for near and far objects, the loss of detail in distant objects may be particularly noticeable with extreme enlargements. Achieving this additional sharpness in distant objects usually requires focusing beyond the hyperfocal distance, with this approach, foreground objects cannot always be made perfectly sharp, but the loss of sharpness in near objects may be acceptable if recognizability of distant objects is paramount. Other authors have taken the position, maintaining that slight unsharpness in foreground objects is usually more disturbing than slight unsharpness in distant parts of a scene. The combination of length, subject distance, and format size defines magnification at the film / sensor plane. DOF is determined by subject magnification at the film / sensor plane, for a given f-number, increasing the magnification, either by moving closer to the subject or using a lens of greater focal length, decreases the DOF, decreasing magnification increases DOF. For a given magnification, increasing the f-number increases the DOF. If the original image is enlarged to make the final image, when focus is set to the hyperfocal distance, the DOF extends from half the hyperfocal distance to infinity, and the DOF is the largest possible for a given f-number. The comparative DOFs of two different format sizes depend on the conditions of the comparison, the DOF for the smaller format can be either more than or less than that for the larger format. In the discussion that follows, it is assumed that the images from both formats are the same size, are viewed from the same distance, and are judged with the same circle of confusion criterion
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Large format
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Large format refers to any imaging format of 4×5 inches or larger. Large format is larger than medium format, the 6×6 cm or 6×9 cm size of Hasselblad, Rollei, Kowa, and Pentax cameras, and much larger than the 24×36 mm frame of 35 mm format. The main advantage of large format, film or digital, is higher resolution at the pixel pitch. A 4×5 inch image has about 16 times the area, and thus 16× the total resolution, of a 35 mm frame. Large format cameras were some of the earliest photographic devices, and before enlargers were common, it was normal to just make 1,1 contact prints from a 4×5, 5×7, or 8×10-inch negative. The most common format is 4×5 inches, which was the size common cameras used in the 1930s-1950s, like the Graflex Speed Graphic and Crown Graphic. Above 8×10 inches, the formats are referred to as Ultra Large Format and may be 11×14, 16×20, or 20×24 inches or as large as film, plates. Many large formats are horizontal cameras designed to make big negatives for contact printing onto press-printing plates, the Polaroid 20×24 camera is one of the largest format instant cameras in common usage and can be hired from Polaroid agents in various countries. Many well-known photographers have used the 235 pounds, wheeled-chassis Polaroid, architectural and close-up photographers in particular benefit greatly from this ability. These allow the front and back of the camera to be shifted up/down and left/right, a number of actions need to be taken to use a typical large format camera, resulting in a slower, often more contemplative, photographic style. A tripod is used for view camera work, but some models are designed for hand-held use. These technical cameras have separate viewfinders and rangefinders for faster handling, in general large format camera use, the scene is composed on the cameras ground glass, and then a film holder is fitted to the camera back prior to exposure. Failure to Polaroid an exposure risks discovery later, at the time of film development, the 4×5 inch sheet film format was very convenient for press photography since it allowed for direct contact printing on the printing plate, hence it was widely used in press cameras. This was done well into the 1940s and 1950s, even with the advent of more convenient, the 35 mm and medium format SLR which appeared in the mid-1950s were soon adopted by press photographers. Large format photography is not limited to film, large digital camera backs are available to fit large format cameras and these are either medium-format digital backs adapted to fit large format cameras, step and repeat Multishot systems, or scanning backs. Scanning backs can take seconds or even minutes to capture an image. When using a Sinar Macroscan unit and 54H data files, over 1 gigabyte of data is produced, high quality fine art prints can be made at sizes in the range of 40x50 from a 4×5 original, and well beyond that for larger negatives. The Library of Congress uses various large format digital scans for American Memories in the current JPEG2000 format, and the older MrSID, JPEG, and TIFF formats
37.
Medium format (film)
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Medium format has traditionally referred to a film format in still photography and the related cameras and equipment that use film. Generally, the term applies to film and digital cameras that record images on media larger than 24 by 36 mm, but smaller than 4 by 5 inches. In digital photography, medium format refers either to cameras adapted from medium-format film photography uses, or to cameras making use of sensors larger than that of a 35 mm film frame. As of 2013, medium-format digital photography sensors were available in sizes of up to 40.3 by 53.7 mm, sensors used in special applications such as spy satellites can be even larger, but are not necessarily described as medium-format equipment. In digital, medium format is an expensive option, with typical brand new all-digital medium-format cameras retailing for $10,000 to $32,000 in 2008. While at one time or another a variety of medium-format film sizes were produced, other sizes are mainly produced for use in antique cameras, and many people assume 120/220 film when the term medium format is used. The general rule with consumer cameras—as opposed to specialized industrial, scientific, and military equipment—is the more cameras sold, medium-format cameras made since the 1950s are generally less automated than smaller cameras made at the same time, having high image quality as their primary advantage. For example, autofocus became available in consumer 35 mm cameras in 1977, but did not reach medium format until the late 1990s, and has never been available in a consumer large format camera. The main benefit of medium-format photography is that, because of the size of the film or digital sensor. This allows for enlargements and smooth gradation without the grain or blur that would characterize similarly enlarged images produced from smaller film formats. The larger size of the film allows for better control of the depth of field. Cameras with a bellows typically support tilt and shift of the lens, together with 1,1 focusing, this permits landscape photography with an extremely large depth of field — from closest foreground to the far horizon — to be achieved. Compared to 35 mm, the drawbacks are accessibility and price. Also, medium-format cameras tend to be bulkier than their 35mm counterpart, medium-format film is usually roll film, typically allowing 8 to 32 exposures on one roll of film before reloading is needed. This is less convenient than 35 mm cartridges, which typically take 12 to 36 pictures on one roll, some companies had bulk film backs that used 70mm double-perforated that allowed up to 75 feet of film to be loaded at one time. While rolls of large format film were produced at one time, their use was specialized, medium-format sheet film was produced for some cameras, but these cameras tend to be smaller, lighter, and easier to use than large format gear. Sheet film was never used in cameras smaller than medium format. Film cost per exposure is related to the amount of film used, thus, the larger the film size
38.
Focal length
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The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a focal length has greater optical power than one with a long focal length. For a thin lens in air, the length is the distance from the center of the lens to the principal foci of the lens. For a converging lens, the length is positive, and is the distance at which a beam of collimated light will be focused to a single spot. For a diverging lens, the length is negative, and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens. The focal length of a lens can be easily measured by using it to form an image of a distant light source on a screen. The lens is moved until an image is formed on the screen. In this case 1/u is negligible, and the length is then given by f ≈ v. Back focal length or back focal distance is the distance from the vertex of the last optical surface of the system to the focal point. For an optical system in air, the focal length gives the distance from the front. If the surrounding medium is not air, then the distance is multiplied by the index of the medium. Some authors call these distances the front/rear focal lengths, distinguishing them from the front/rear focal distances, defined above. In general, the length or EFL is the value that describes the ability of the optical system to focus light. The other parameters are used in determining where an image will be formed for an object position. The quantity 1/f is also known as the power of the lens. The corresponding front focal distance is, FFD = f, in the sign convention used here, the value of R1 will be positive if the first lens surface is convex, and negative if it is concave. The value of R2 is negative if the surface is convex
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Hyperfocal distance
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In optics and photography, hyperfocal distance is a distance beyond which all objects can be brought into an acceptable focus. When the lens is focused at this distance, all objects at distances from half of the distance out to infinity will be acceptably sharp. Definition 2, The hyperfocal distance is the distance beyond which all objects are acceptably sharp, the distinction between the two meanings is rarely made, since they have almost identical values. The value computed according to the first definition exceeds that from the second by just one focal length, as the hyperfocal distance is the focus distance giving the maximum depth of field, it is the most desirable distance to set the focus of a fixed-focus camera. The hyperfocal distance is entirely dependent upon what level of sharpness is considered to be acceptable, the criterion for the desired acceptable sharpness is specified through the circle of confusion diameter limit. This criterion is the largest acceptable spot size diameter that a point is allowed to spread out to on the imaging medium. For practical purposes, there is difference between the first and second definitions. The following derivations refer to the accompanying figures, for clarity, half the aperture and circle of confusion are indicated. An object at distance H forms an image at distance x. Here, objects at infinity have images with a circle of confusion indicated by the ellipse where the upper red ray through the focal point intersects the blue line. Objects at infinity form sharp images at the length f. Here, an object at H forms an image with a circle of confusion indicated by the ellipse where the lower red ray converging to its sharp image intersects the blue line. With the formula for the Definition 2, the result is 10417 mm and this continues on through all successive 1/x values of the hyperfocal distance. Piper calls this phenomenon consecutive depths of field and shows how to test the idea easily and this is also among the earliest of publications to use the word hyperfocal. The figure on the right illustrates this phenomenon, the concepts of the two definitions of hyperfocal distance have a long history, tied up with the terminology for depth of field, depth of focus, circle of confusion, etc. Here are some selected early quotations and interpretations on the topic, thomas Sutton and George Dawson define focal range for what we now call hyperfocal distance, Focal Range. In every lens there is, corresponding to a given apertal ratio, for instance, in a single view lens of 6 inch focus, with a 1/4 in. Stop, all situated at distances lying between 20 feet from the lens and an infinite distance from it are in equally good focus
