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Photography is the technique of recording, by chemical, mechanical or digital means, a permanent image on a layer of material sensitive to light exposure.
The word comes from the Greek words φωτος photos ("light"), and γραφις graphis ("stylus", "paintbrush") or γρφη graphê, together meaning "drawing with light" or "representation by means of lines", "drawing".
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. And one can place objects directly on the glass of a scanner to produce pictures electronically.
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:
The controls are usually inter-related, for example brightness is aperture multiplied by shutter speed, and varying the focal length of the lens will allow greater control over the depth of field.
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 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.
Growth of popular photography has closely paralled the growth of telephony. The practice of both prodominately concerns communication with friends and family. In the U.S., the share of households with a camera and with a telephone was about 1% and 2%, respectively, in 1890, 44% and 35%, respectively in 1938, and 94% for both in 1995. Across this same period in the U.S., the ratio of residential telephone minutes to end-user photographs rose from 31 to 80 from 1890 to 1939, and remained roughly constant through 1995, when the ratio was 71 (for statistical sources and calulations, see ). Since telephone conversations average about 150 words per minute, the data indicate that a picture is associated with about twelve thousand words of telephone conversation. "A picture is worth a thousand words" is a popular English folk saying, variously described as a Chinese proverb and a saying of a famous Japanese philosopher. This saying actually arose from advertisements in a U.S. commercial media journal in the mid-1920s (see ) Nonetheless, a close relationship between pictures and words in the human process of making sense seems to be an important and underappreciated aspect of human physiology and behavior.
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.
One of the early methods of taking color photos was to use three cameras. Each camera would have a color filter in front of the lens. This technique provides the photographer with the three basic channels required to recreate a color image in a darkroom or processing plant.
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.
The market for photographic services demonstrates the cliché "one picture is worth a thousand words," which has an interesting basis in the #History of photography. Magazines and newspapers, companies putting up Web sites, advertising agencies and other groups pay for photography.
Many people take photographs for self-fulfillment or for commercial purposes. Organizations with a budget and a need for photography have several options: they can assign a member of the organization, hire someone, or obtain rights to stock photographs.
Traditionally, the product of photography has been called a photograph. The term photo is a convenient abbreviation. Many people also call them pictures.
In digital photography, the term image has begun to replace photograph. This term is neither more nor less correct than photograph, either in film or digital photography. (The term image is traditional in geometric optics.)
The aesthetics of photography is a matter that continues to be discussed. Is photography an art - or is it just the mechanical reproduction of an image? If photography is authentically art, what makes a photograph beautiful? Is there a kinship between the beauty of an Atget and a Rembrandt?
The controversy began with the earliest images "written with light": , , and others among the very earliest photographers were met with wonder, but some questioned if it was really art.
Clive Bell in his classic essay "Art" states that only one thing can distinguish art from what is not art: "significant form." Bell wrote: "There must be some one quality without which a work of art cannot exist; possessing which, in the least degree, no work is altogether worthless. What is this quality? What quality is shared by all objects that provoke our aesthetic emotions? What quality is common to Sta. Sophia and the windows at Chartres, Mexican sculpture, a Persian bowl, Chinese carpets, Giotto's frescoes at Padua, and the masterpieces of Poussin, Piero della Francesca, and Cezanne? Only one answer seems possible - significant form. In each, lines and colours combined in a particular way, certain forms and relations of forms, stir our aesthetic emotions." .
Others have since examined if this criterion be applied to photography. This question has been dealt with by the Aesthetic Realism understanding of beauty. Some of the most important writing on this subject is to be found on the web sites of Camera
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