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, mechanical or digital means, a permanent image on a layer of material sensitive to light exposure.
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.
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.
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 KodakBrownie 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 filmLeica camera in 1925.
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.
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.