What is "telephoto lens"

Telephoto lens \Tel`e*pho"to lens\ n. a special compound camera lens with a long effective focal length but used in a camera with a short focal length, allowing large images to be obtained of distant objects when used in a camera in place of an ordinary lens; -- called also telephotographic lens.

n. 1 (context photography English) A lens having a long focal length which produces a magnify view of distant objects. 2 (context photography English) A lens which produces a magnified view of distant objects and which is sufficiently compact to have a physical length shorter than its focal length (as distinct from a long-focus lens).

n. a camera lens that magnifies the image [syn: zoom lens]

In photography and cinematography, a telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. 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 in a much shorter overall design. The angle of view and other effects of long-focus lenses are the same for telephoto lenses of the same specified focal length. Long-focal-length lenses are often informally referred to as telephoto lenses although this is technically incorrect: a telephoto lens specifically incorporates the telephoto group.

Telephoto lenses are sometimes broken into the further sub-types of medium telephoto: lenses covering between a 30° and 10° field of view (67mm to 206mm in 35mm film format), and super telephoto: lenses covering between 8° through less than 1° field of view (over 300mm in 35mm film format).