Focal length is the distance between the focal point of a lens and the film plane when the lens is focused at infinity. It is used to designate the relative size and angle of view of a lens, expressed in millimeters (mm). A particular lens focal length (e.g. 35mm, 50mm, 105mm, 600mm, etc.) can generally be found engraved or printed on the front of the lens.Photo Tips
Sometimes called FLM - See Format Factor below.
See Format Factor below.
The distance from the lens to the film plane or sensor that focuses light at infinity. The length, expressed in millimeters, is more useful as an indication of the angle of view of a particular lens. A shorter focal length lens, such as a 28mm, offers a wider angle of view than a longer one, such as 100mm.
A camera s lens focuses light onto a specific plane where the film or sensor is located.
A camera shutter situated directly in front of the digital sensor or film, composed of an opaque curtain that contains a slit that moves directly across in front of the sensor or film, permitting light to strike the sensor or film. Some cameras employ two curtains.