Diaphragm (optics)

This article is a translation from the Dutch article on diafragma

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In optics, a diaphragm is a (usually round or polygonal) opening in the lightpath of a lens or objective that can regulate the amount of light that passes. The centre of the diaphragm coincides with the optical axis of the lens system.

Related Topics:
Optics - Polygon - Lens - Objective - Optical axis

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Many cameras have an adjustable diaphragm to control the amount of light, which can also be regulated by adjusting the shutter time. The principle is identical to that of the iris in the human eye.

Related Topics:
Camera - Shutter time - Iris

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A small diaphragm reduces the amount of light, but also reduces the influence of aberrations of the optical lens system and increases the depth of field. The reduced light intensity will however require the shutter time to be increased, which leads to increased blurring if the subject of the photograph or the camera moves during the exposure.

Related Topics:
Aberrations - Depth of field

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