1.
Nikkormat
–
Nikkormat was a brand of cameras produced by the Japanese optics company Nippon Kogaku K. K. as a consumer version of the professional Nikon brand. Nikkormat cameras, produced from 1965 until 1978, were simpler and more affordable than Nikon-branded cameras, the Nikkormat FT was an all-metal, mechanically controlled, manual focus SLR with match-needle exposure control, manufactured in Japan from 1965 to 1967. It was available in two colors, black with chrome trim and all black, the unmetered version was designated Nikkormat FS. The FT had dimensions of 95 mm height,146 mm width,54 mm depth and 745 g weight, the FT used a metal-bladed, vertical travel, focal plane shutter with a speed range of 1 to 1/1000 second plus Bulb and flash X-sync of 1/125th second. The Nikkormat F-series had a shutter speed ring concentric with the lens mount, the photographer would adjust the shutter speed to freeze or blur motion and/or the lens aperture f-stop to control depth of field until the needle was centered between two pincer-like brackets. The needle array was duplicated in a window next the film rewind crank to allow exposure control without looking through the viewfinder. The meter was turned on by pulling the film wind lever out to the ready position. This was very advanced in 1965 and proved to be remarkably long-lived, Nippon Kogaku used it for all versions of the Nikkormat FT with incremental improvements. The Nikon FM, FM2 and FM2N of the succeeding Nikon compact F-series SLRs used an improved viewfinder only, the FTs viewfinder also had a fixed focusing screen with Nippon Kogakus then standard central 4 mm microprism focusing aid plus 12 mm matte focusing surface. The Nikkormat FT accepted all lenses with the Nikon F bayonet mount, the FT had a mirror lockup allowing its use with some specialised lenses for which an auxiliary viewfinder was provided. The FT was Nippon Kogakus first SLR with a built-in TTL light meter, as such, Nippon Kogaku could not find a way to automatically synchronize their Nikkor Auto lenses aperture information with the FT body. Therefore, mounting lenses required a special preparatory procedure, first, the lens maximum aperture must set against the film speed scale on the FTs shutter speed ring. Note that the maximum aperture had to be reset every time the lens was changed. This was very inconvenient compared to some other SLRs of the 1960s, although most AF Nikkor lenses will mount and manually focus on the FT, the combination cannot provide open aperture metering, only stop down metering. However, the FT did not have an accessory shoe to mount flash units. The Nikkormat accessory shoe must be screwed to the top of the pentaprism cover via the eyepiece first, note that this shoe only mounts the flash. A PC cord must still be plugged into the appropriate PC terminal and this was normal for most SLRs of the 1960s. The Nikkormat FS, manufactured from 1965 to 1971, was an FT stripped of the light meter with its exposure information system
2.
Photography
–
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
3.
Camera
–
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
4.
Shutter (photography)
–
A shutter can also be used to allow pulses of light to pass outwards, as seen in a movie projector or a signal lamp. A shutter of variable speed is used to control exposure time of the film, the shutter is so constructed that it automatically closes after a certain required time interval. The speed of the shutter is controlled by a ring outside the camera, focal-plane shutters are mounted near the focal plane and move to uncover the film or sensor. Behind-the-lens shutters were used in cameras with limited lens interchangeability. Shutters in front of the lens, sometimes simply a lens cap that is removed and replaced for the long exposures required, were used in the days of photography. Other mechanisms than the aperture and the sliding curtains have been used. The time for which a shutter remains open is determined by a timing mechanism and these were originally pneumatic or clockwork, but since the late twentieth century are mostly electronic. The reciprocal of time in seconds is often used for engraving shutter settings. For example, a marking of 250 denotes 1/250 and this does not cause confusion in practice. The exposure time and the aperture of the lens must together be such as to allow the right amount of light to reach the film or sensor. Additionally, the time must be suitable to handle any motion of the subject. Usually it must be fast enough to freeze rapid motion, unless a controlled degree of motion blur is desired, most shutters have a flash synchronization switch to trigger a flash, if connected. This was quite a complicated matter with mechanical shutters and flashbulbs which took a time to reach full brightness. Special flashbulbs were designed which had a burn, illuminating the scene for the whole time taken by a focal plane shutter slit to move across the film. These problems were solved for non-focal-plane shutters with the advent of electronic flash units which fire virtually instantaneously. When using a focal-plane shutter with a flash, if the shutter is set at its X-sync speed or slower the whole frame will be exposed when the flash fires, some electronic flashes can produce a longer pulse compatible with a focal-plane shutter operated at much higher shutter speeds. The focal-plane shutter will still impart focal-plane shutter distortions to a moving subject. Cinematography uses a rotary shutter in movie cameras, a continuously spinning disc which conceals the image with a reflex mirror during the intermittent motion between frame exposure
5.
Photographic film
–
This article is mainly concerned with still photography film. For motion picture film, please see film stock, photographic film is a strip or sheet of transparent plastic film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of the crystals determine the sensitivity, contrast, the emulsion will gradually darken if left exposed to light, but the process is too slow and incomplete to be of any practical use. Instead, a short exposure to the image formed by a camera lens is used to produce only a very slight chemical change. This creates an invisible latent image in the emulsion, which can be developed into a visible photograph. In addition to light, all films are sensitive to ultraviolet, X-rays. Unmodified silver halide crystals are only to the blue part of the visible spectrum. This problem was overcome with the discovery that certain dyes, called sensitizing dyes, first orthochromatic and finally panchromatic films were developed. Panchromatic film renders all colors in shades of gray approximately matching their subjective brightness, by similar techniques special-purpose films can be made sensitive to the infrared region of the spectrum. In black-and-white photographic film there is one layer of silver halide crystals. When the exposed silver halide grains are developed, the silver halide crystals are converted to metallic silver, color film has at least three sensitive layers, incorporating different combinations of sensitizing dyes. Typically the blue-sensitive layer is on top, followed by a filter layer to stop any remaining blue light from affecting the layers below. Next come a green-and-blue sensitive layer, and a sensitive layer. During development, the silver halide crystals are converted to metallic silver. Because the by-products are created in direct proportion to the amount of exposure and development, following development, the silver is converted back to silver halide crystals in the bleach step. It is removed from the film during the process of fixing the image on the film with a solution of ammonium thiosulfate or sodium thiosulfate, fixing leaves behind only the formed color dyes, which combine to make up the colored visible image. Later color films, like Kodacolor II, have as many as 12 emulsion layers, the earliest practical photographic process, the daguerreotype, introduced in 1839, did not use film. The light-sensitive chemicals were formed on the surface of a copper sheet
6.
Image sensor
–
An image sensor or imaging sensor is a sensor that detects and conveys the information that constitutes an image. It does so by converting the variable attenuation of light waves into signals, the waves can be light or other electromagnetic radiation. As technology changes, digital imaging tends to replace analog imaging, early analog sensors for visible light were video camera tubes. Currently, used types are semiconductor charge-coupled devices or active pixel sensors in complementary metal–oxide–semiconductor or N-type metal-oxide-semiconductor technologies, analog sensors for invisible radiation tend to involve vacuum tubes of various kinds. Digital sensors include flat panel detectors, today, most digital cameras use a CMOS sensor, because CMOS sensors perform better than CCDs. An example is the fact that they incorporate an integrated circuit, CCD is still in use for cheap low entry cameras, but weak in burst mode. Both types of sensor accomplish the task of capturing light. Each cell of a CCD image sensor is an analog device, when light strikes the chip it is held as a small electrical charge in each photo sensor. This process is repeated until all the lines of pixels have had their charge amplified. A CMOS image sensor has an amplifier for each compared to the few amplifiers of a CCD. Some CMOS imaging sensors also use Back-side illumination to increase the number of photons that hit the photodiode, CMOS sensors can potentially be implemented with fewer components, use less power, and/or provide faster readout than CCD sensors. They are also vulnerable to static electricity discharges. Another approach is to utilize the very fine dimensions available in modern CMOS technology to implement a CCD like structure entirely in CMOS technology and this can be achieved by separating individual poly-silicon gates by a very small gap. These hybrid sensors are still in the phase and can potentially harness the benefits of both CCD and CMOS imagers. There are many parameters that can be used to evaluate the performance of a sensor, including dynamic range, signal-to-noise ratio. For sensors of comparable types, the ratio and dynamic range improve as the size increases. In order to avoid interpolated color information, techniques like color co-site sampling use a mechanism to shift the color sensor in pixel steps. 3CCD, using three discrete image sensors, with the color separation done by a dichroic prism, while in general digital cameras use a flat sensor, Sony prototyped a curved sensor in 2014 to reduce/eliminate Petzval field curvature that occurs with a flat sensor
7.
F-number
–
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
8.
Film speed
–
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
9.
Luminance
–
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light passes through, is emitted or reflected from a particular area. The SI unit for luminance is candela per square metre, a non-SI term for the same unit is the nit. The CGS unit of luminance is the stilb, which is equal to one candela per square centimetre or 10 kcd/m2, luminance is often used to characterize emission or reflection from flat, diffuse surfaces. The luminance indicates how much power will be detected by an eye looking at the surface from a particular angle of view. Luminance is thus an indicator of how bright the surface will appear, in this case, the solid angle of interest is the solid angle subtended by the eyes pupil. Luminance is used in the industry to characterize the brightness of displays. A typical computer display emits between 50 and 300 cd/m2, the sun has luminance of about 1. 6×109 cd/m2 at noon. Luminance is invariant in geometric optics and this means that for an ideal optical system, the luminance at the output is the same as the input luminance. For real, passive, optical systems, the luminance is at most equal to the input. As an example, if one uses a lens to form an image that is smaller than the source object, the luminous power is concentrated into a smaller area, meaning that the illuminance is higher at the image. The light at the plane, however, fills a larger solid angle so the luminance comes out to be the same assuming there is no loss at the lens. The image can never be brighter than the source, if light travels through a lossless medium, the luminance does not change along a given light ray. In the case of a perfectly diffuse reflector, the luminance is isotropic, then the relationship is simply L v = E v R / π A variety of units have been used for luminance, besides the candela per square metre. One candela per square metre is equal to, 10−4 stilbs π apostilbs π×10−4 lamberts 0.292 foot-lamberts Retinal damage can occur when the eye is exposed to high luminance, damage can occur due to local heating of the retina. Photochemical effects can cause damage, especially at short wavelengths. Also available in PDF form and Google Docs online version Autodesk Design Academy Measuring Light Levels
10.
Exposure (photography)
–
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
.jpg)
