Photography is the process of making pictures by means of the action of light. It involves recording light patterns, as reflected from objects, onto a sensitive medium through a timed exposure. The process is done through mechanical, chemical or digital devices commonly known as cameras. Most commonly a camera or camera obscura is the image forming device and photographic film or a digital storage card is the recording medium, although 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. After processing, this produces an image whose contents are acceptably sharp, bright and composed to achieve the objective of taking the photograph. Changing any of these will, therefore, alter the exposure. Many lenses will automatically adjust the aperture to account for changes in focus, and some will do so for changes in zoom as well. In order to achieve a given exposure, various combinations of shutter speed and aperture could be used. 120th of a second yield the same amount of light. However, the combination chosen impacts the final result. If the aperture is made smaller, or a shorter lens is used, then both the subjects eyes and nose can be brought into focus at the same time.

If a very small aperture is used, such as a pinhole, then a very wide range of distance can be brought into focus at once. Finally, image capture is only half of the image forming process. In addition to the camera controls, the processing variables have a significant impact on the final result. Uses of photography Photography can be classified under imaging technology and has gained the interest of scientists and artists from its inception. Military, police and security forces use photography for surveillance, recognition and data storage. Invention Main article: History of the camera Chemical photography Projecting images onto surfaces has been done for centuries. The camera obscura and the camera lucida were used by artists to trace scenes as early as the 16th century. These early cameras did not fix an image in time; they only projected what was before an opening in the wall of a darkened room onto a surface. In effect, the entire room was turned into a large pinhole camera. It was produced with a camera, and required an eight hour exposure in bright sunshine.

Johann Heinrich Schultz discovery in 1724 that a silver and chalk mixture darkens when exposed to light.

Jacques Daguerre, in Paris, refined the existing silver process in a partnership. While he had no scientific background, Daguerre made two pivotal contributions to the process. By then bathing the plate in a salt bath the image could be fixed. In 1839 Daguerre announced that he had invented a process using silver on a copper plate called the Daguerreotype. The French government bought the patent and immediately made it public domain. Across the English Channel, William Fox Talbot had earlier discovered another means to fix a silver process image but had kept it secret.