Angle of View
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It is the extent of the view taken in by a lens. It is determined by the focal length of a lens and film format. A “standard” 50mm lens for 35mm film has an angle of view equal to the diagonal of the film, which is 70° horizontally and 58° vertically. A 135mm "short telephoto" lens has a reduced angle of view of 29° horizontally and 23° vertically.
