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A telephoto lens, also known as telelens, is a specific type of a long-focus lens used in photography and cinematography, in which the physical length of the lens is shorter than the focal length. [ 1 ] : 93 This is achieved by incorporating a special lens group known as a telephoto group that extends the light path to create a long-focus lens ...
The design of telephoto lenses reduces some of the problems encountered by designers of long-focus lenses. In particular, telephoto lenses are typically much shorter and may be lighter for equivalent focal length and aperture. However telephoto designs increase the number of lens elements and can introduce flare and exacerbate some optical ...
As with other types of camera lenses, the focal length is usually expressed in a millimeter value written on the lens, for example: a 500 mm lens. The most common type of long-focus lens is the telephoto lens, which incorporate a special lens group known as a telephoto group to make the physical length of the lens shorter than the focal length. [4]
Telephoto lenses using diffractive elements to minimize chromatic aberration are commercially available from Canon and Nikon for interchangeable-lens cameras; these include 800mm f/6.3, 500mm f/5.6, and 300mm f/4 models by Nikon (branded as "phase fresnel" or PF), and 800mm f/11, 600mm f/11, and 400mm f/4 models by Canon (branded as ...
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 ...
These lenses use some form of the cassegrain design which greatly reduces the physical length of the optical assembly, partly by folding the optical path, but mostly through the telephoto effect of the convex secondary mirror which multiplies the focal length many times (up to 4 to 5 times). [12]