Using lenses of different focal lengths changes the apparent size of the subject and the extent of the scene visible in the frame. The angle of view (diagonal angle of view) is a measure of the extent of the scene visible in the frame, expressed as an angle. For example, a standard FX-format lens with a focal length of 50 mm has a angle of view of 46° when mounted on a 35 mm camera. A lens with a shorter focal length (a wide-angle lens) would have a wider angle of view and make the subject appear smaller, while a lens with a longer focal length (a telephoto lens) would have a narrower angle of view and make the subject appear larger.