
The image area on the sensor differs between the Full Frame and Cropped formats in terms of physical size. The Full Frame format has an image area based on the 35mm (36 x 24) image circle, the image area of the Cropped format is approximately 24 x 16 mm.
Full Frame formatThe larger Full Frame image sensor is virtually the same size as the 35mm [135] film format which means that the focal length of a lens used on either format will be virtually the same. Many higher end auto focus and manual focus lenses can be used with Full Frame format cameras.
Cropped frame lenses are engineered and optimised for use on both Full Frame format and Cropped format digital SLR cameras. When mounted on an Full Frame format digital SLR, the camera's Cropped Mode is automatically engaged, altering the image capture area accordingly. This image crop is also reflected in the cameras viewfinder display with the image area not captured greyed out.
Cropped formatAll lenses designated as Cropped type can be used with Cropped format digital SLR cameras. Many lenses designed for Full Frame or 35mm [135] film formats can also be used with Cropped format digital SLR cameras. The effect of using a lens on a Cropped format camera will produce a magnification of the focal length of the lens by a factor of around 1.5x (eg. a 50mm lens will produce the equivilant of a 75mm focal length).