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A zoom lens is a system of camera lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed-focal-length (FFL) lens . A true zoom lens or optical zoom lens is a type of parfocal lens, one that maintains focus when its focal length changes. [1]
Zoom lenses (sometimes referred to as "true" zoom) are ideally parfocal, in that focus is maintained as the lens is zoomed (i.e., focal length and magnification changed), which is convenient and has the advantage of allowing more accurate focusing at maximal focal length then zooming back to a shorter focal length to compose the image.
There is no precise definition of the term, but lenses marketed as "standard zoom" usually cover a range of at least 30mm to 70mm in terms of 35mm equivalent focal length with an optical zoom ratio of 2.5× (e.g. 28-70mm) to 5× (e.g. 24-120mm) — the most common being 3× (e.g. 24-70mm). [1]
This is a list of smartphones with a telephoto lens that offers a focal length (35mm equivalent) of at least 100mm or "4× optical zoom" with an imaging area equivalent to a 1/3.5″ or larger sensor. Smartphone lenses are often marketed in terms of "optical zoom" [1] relative to the phone's main camera. For example, 120mm is usually referred ...
They began breaking new ground around 1960: the Nippon Kogaku Auto-Nikkor 8.5–25 cm f/4-4.5 (1959), for the Nikon F, was the first telephoto zoom lens for 35mm still cameras (and second zoom after the Zoomar), [141] the Canon 50mm f/0.95 (1961), for the Canon 7 35mm RF, with its superwide aperture, was the first Japanese lens a photographer ...
1959 Voigtländer Bessamatic, fitted with DKL-mount Zoomar lens (36~82 mm, f /2.8), first production zoom lens for still photography. The Zoomar lens was the first commercially successful zoom lens, designed by optical engineer Frank G. Back as an outgrowth of his research on viewfinders and variable focal length projectors for the United ...