The focal length is given in millimetres and is the distance between lens and focal point.
- Small focal length:
- Large field of view
- Objects are reduced in size
- Large depth of field (expansion of the sharp area)
- Long focal length
- Small field of view
- Objects are enlarged
- Small depth of field (expansion of the sharp area)
A lens with a short focal length, e.g. 18mm, shows a large field of view. This lens is a wide-angle lens, suitable for photographing large subjects, e.g. landscapes, buildings etc. The millimetre specifications always refer to cameras in 35mm format with full format sensor (corresponds to the size of 35mm film negatives)
The 50mm lens comes closest to the angle of view of the human eye and is also called normal lens.
Telephoto lenses with focal lengths from 70mm are very suitable for animal, sports and portrait photography.
Zoom lenses allow the focal length to be continuously extended or shortened within a certain range, e.g. 70 – 120mm tele zoom.