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The pupil magnification of an optical system is the ratio of the diameter of the
exit pupil In optics, the exit pupil is a virtual aperture in an optical system. Only rays which pass through this virtual aperture can exit the system. The exit pupil is the image of the aperture stop in the optics that follow it. In a telescope or compou ...
to the diameter of the
entrance pupil In an optical system, the entrance pupil is the optical image of the physical aperture stop, as 'seen' through the front (the object side) of the lens system. The corresponding image of the aperture as seen through the back of the lens system i ...
. The pupil magnification is used in calculations of the effective f-number, which affects a number of important elements related to optics, such as
exposure Exposure or Exposures may refer to: People * The Exposures, a pseudonym for German electronic musician Jan Jeline Arts, entertainment, and media Films * ''Exposure'' (film), a 1932 American film * ''Exposure'', another name for the 1991 movie ...
, diffraction, and
depth of field The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera. Factors affecting depth of field For cameras that can only focus on one object di ...
. For all symmetric lenses, and for many conventional
photographic lens A camera lens (also known as photographic lens or photographic objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capa ...
es, the pupils appear the same size and so the pupil magnification is approximately 1.


See also

*
Magnification Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in si ...


External links


Photo.net lens tutorial
Geometrical optics {{photography-stub