35 mm equivalent focal length

The magnification of a zoom lens depends not only on the focal length, but also the physical size of the CCD. For that reason, all manufacturers offer lens focal length in "35 mm equivalent". This is the focal length on a 35-mm film camera that would give the same magnification. Expressing focal lengths in 35 mm equivalent makes it easy to compare cameras with different size sensors's.

An "35mm equivalent" focal length of 130 mm will provide the same composition on any digital camera, regardless of sensor size.

A related term is "crop factor." The crop factor is the ratio of the image diagonal of the image region on 35 mm film to image diagonal of the sensor size of the camera in question. If your camera has a crop factor of 1.5, multiple the focal length of its lens by 1.5 to find the lens's 35mm equivalent focal length.