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Photography (Greek "drawing with light" from
photos = light, and graphis = stylus, paintbrush or graphê = representation by means of lines,
drawing) is the technique of recording, by chemical or mechanical means, a permanent image on a layer of material sensitive to
light exposure.
Image forming devices
Most commonly a camera or camera obscura is the image forming device and photographic film or a digital storage card is the recording medium, but other methods are available. For
instance, the photocopy or xerography machine forms permanent images but uses the transfer of static electrical charges rather than photographic film, hence the term electrophotography. The rayographs published by Man Ray in 1922 are images produced by the shadows of
objects cast on the photographic paper, without the use of a camera.
Photographers control the camera to expose the light recording material (usually film) to light. After processing, this
produces an image whose contents are acceptably sharp, bright and composed to achieve the objective of taking the photograph.
The controls include:
- Point of focus
- Aperture of the lens
- Length of exposure
- Focal length of the lens(Telescopic, zoom, or wide angle)
- Sensitivity of the film
The controls are usually inter-related, for example brightness is aperture multiplied by length of exposure, and varying the
focal length of the lens will allow greater control over the depth of focus.
Uses of photography
Photography can be classified under imaging technology and
has gained the interest of scientists and artists from its inception. Scientists have used its capacity to make accurate
recordings, such as Eadweard Muybridge in his study of human
and animal locomotion (1887). Artists have been equally interested by this aspect but have also tried to explore other avenues
than the photo-mechanical representation of reality, such as the pictorialist movement. Military, police and security forces use photography for surveillance, recognition and
data storage.
History of photography
The first photograph is considered to be an image produced in 1825 by Nicéphore Niepce on a
polished pewter plate covered with a petroleum derivative called bitumen of Judea. It was produced with a
camera, and required an eight hour exposure in bright sunshine. In 1839 Jacques Daguerre
developed a process using silver on a copper plate called the Daguerreotype. Almost at the same time, William
Fox Talbot developed a different process called the calotype, using paper
sheets covered with silver chloride. This process is much closer to the photographic process in use nowadays, as it produces a
negative image that can be reused to produce several positive prints. Hippolyte Bayard also developed a method of photography, but delayed announcing it and so was not
recognized as its inventor.
The Daguerreotype proved more popular as it responded to the demand for portraiture emerging from the middle classes during
the Industrial Revolution. This demand, that could not be
met in volume and in cost by oil painting, may well have been the push for the development of photography. Neither of the
techniques involved, the camera obscura, and the photo sensitivity of silver salts, were 19th century discoveries. Camera obscura were used by artists in the 16th century, as an aid to sketches for paintings, and the photo-sensitivity of a silver nitrate solution was
observed by Johann Schultze in 1724.
Ultimately, the modern photographic process came
about from a series of refinements and improvements on the foundations laid by William Fox Talbot. Photography became available
for the mass-market in 1901 with the introduction of the Kodak Brownie camera, and, more importantly, with the industrialisation of
film processing and printing. Very little has changed in principle since then, though color film has become the standard, and
automatic focus and automatic exposure. Digital recording of images is becoming
increasingly prevalent, as electronic sensors become more sensitive and able to provide definition approaching chemical
methods.
For the enthusiast photographer processing black and white film, little has changed since the introduction of the 35mm film Leica camera in 1925.
Color photography
Color photography was explored throughout the 1800s. Initial experiments in color could not fix the photograph and prevent the color from
fading. The first permanent color photo was taken in 1861 by the physicist James Clerk Maxwell. The first color film, Autochrome, did not reach the market until 1907 and was based on dyed dots of potato starch. The first modern color film, Kodachrome, was introduced in 1935 based on three colored emulsions. Most
modern color films, except Kodachrome, are based on technology developed for Agfacolor in 1936. Instant color
film was introduced by Polaroid in 1963.
Color photography may form images as a positive transparency, intended for use in a slide projector or as color negatives, intended for use in creating positive color enlargements on
specially coated paper. The latter is now the most common form of film (non-digital) color photograpy, owing to the introduction
of automated photoprinting equipment.
Digital photography
Traditional photography was a considerable burden for photographers
working at remote locations (such as press correspondents) without access to processing facilities. With increased competition
from television, there was pressure to deliver their images to newspapers ever faster. Photo-journalists at remote locations
would carry a miniature photo lab with them, and some means of transmitting their images down the telephone line. In 1990, Kodak unveiled the DCS 100, the first commercially available digital camera. Its cost precluded any use other than photojournalism and professional applications, but commercial digital photography was born.
In 10 years, digital cameras have become consumer products, and they are likely to gradually replace their traditional
counterparts in most applications as the price of electronic components goes down and the image quality improves.
Kodak announced in January 2004 that it would no longer produce reloadable 35-millimeter cameras after the end of that year.
However, "wet" photography will endure, as dedicated amateurs and skilled artists preserve the use of traditional materials and
techniques.
See also
Basic topics in photography
Famous photographers
Historical
Technique(s)
Photographic products
Related topics
External links
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