Editing Camera lens (section)

===Zoom===
{{Main|Zoom lens}}
Some lenses, called '''zoom lenses''', have a focal length that varies as internal elements are moved, typically by rotating the barrel or pressing a button which activates an [[electric motor]]. Commonly, the lens may zoom from moderate wide-angle, through normal, to moderate telephoto; or from normal to extreme telephoto. The zoom range is limited by manufacturing constraints; the ideal of a lens of large maximum aperture which will zoom from extreme wideangle to extreme telephoto is not attainable. Zoom lenses are widely used for small-format cameras of all types: still and cine cameras with fixed or interchangeable lenses. Bulk and price limit their use for larger film sizes. Motorized zoom lenses may also have the focus, iris, and other functions motorized.