The field of view that the lens will provide changes with the focal length of the lens. There are three basic classifications based on the relationship to the diagonal size of the film or sensor size of the camera to the focal length of the lens: Normal lens: angle of view of about 50° (called normal because this angle considered roughly equivalent to human vision) and a focal length approximately equal to the diagonal of the film or sensor. Wide-angle lens: angle of view wider than 60° and focal length shorter than a normal lens. Long focus lens: angle of view narrower than a normal lens. This is any lens with a focal length longer than the diagonal measure of the film or sensor. The most common type of long focus lens is the telephoto lens, a design that uses a special telephoto group to be physically shorter than its focal length.
The field of view that the lens will provide changes with the focal length of the lens. There are three basic classifications based on the relationship to the diagonal size of the film or sensor size of the camera to the focal length of the lens: Normal lens: angle of view of about 50° (called normal because this angle considered roughly equivalent to human vision) and a foca.l length approximately equal to the diagonal of the film or sensor. Wide-angle lens: angle of view wider than 60° and focal length shorter than a normal lens. Long focus lens: angle of view narrower than a normal lens. This is any lens with a focal length longer than the diagonal measure of the film or sensor The most common type of long focus lens is the telephoto lens, a design that uses a special telephoto group to be physically shorter than its focal length.