NSL Photography's™ Glossary of Photographic Terms - Z

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Zoom Lens
A zoom lens is a  lens with the ability to vary its focal length (and thus angle of view), as opposed to a fixed focal length (FFL) or prime lens. A high quality zoom lens, also called a parfocal lens, is one which its maintains focus as its focal length is adjusted by the photographer. A lessor quality zoom lens which loses focus during zooming is called a varifocal lens.

Zoom lenses in digital point and shoot cameras are often described by the ratio of their longest to shortest focal lengths. For example, a zoom lens with focal lengths ranging from 100 mm to 400 mm can be described as a 4:1 or "4×" zoom.

Zoom lenses are often confused with telephoto lenses, those with a narrow angle of view which magnify the subject of the photograph. While some zoom lenses have a strictly telephoto range of focal lengths, some have a strictly wide-angle ranges, while others range from wide-angle to telephoto. Zoom lenses are popular because they can take the place of numerous lenses of fixed focal lengths, and help the photographer avoid having to switch lenses as necessary. Amateur photographers particular like zooms lenses to reduce their cost of lens for the photographer. Zoom lenses on digital point and shoot cameras allow them to have great flexibility, adding the capability to obtain wide angle and telephoto images.

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