As focal length changes, the amount of the subject captured by the lens (the viewing angle) also changes. The shortest focal length, or "ultra wide-angle"lenses, range from 14mm to 20mm, and are followed by "wide-angle" lenses from 24mm to 35mm, and then "standard" lenses from 45 to 70mm, which are similar to the field of view of the human eye. Next are "telephoto" lenses reaching up to 300mm, and finally "super telephoto" lenses covering focal lengths of 300mm and greater.a total of five groups. Furthermore, different focal lengths also produce varying levels of perspective and depth of field, which in turn have a large effect on the image's expression.