Photography

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.

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, 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.

Related Topics:
Camera - Camera obscura - Photographic film - Photocopy - Xerography - Electrical charges - Electrophotography - Rayographs - Man Ray - 1922

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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.

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The controls include:

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• Focus
• Aperture of the lens
• Duration of exposure (or shutter speed)
• Focal length of the lens (telephoto, macro, wide angle, or zoom)
• Sensitivity of the medium to light intensity and color

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.

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