Focal length measures the distance between the camera lens and the camera chip. It describes the angle of view of the camera eye. Camera lenses are categorised according to their focal length.

 

A normal camera lens has a focal length of 50mm and thus corresponds approximately to the viewing angle of the human eye of 46 degrees.

 

The shorter the focal length, i.e. the smaller the number, the larger the angle of view, i.e. the visible area. Wide-angle lenses therefore have a focal length of less than 50mm. For most amateur photographers, a digital camera with a lens from 24 or 28mm is useful.

The telephoto lens has a focal length of more than 50mm and thus zooms in on distant objects. This reduces the angle of view accordingly.

 

The focal length specifications originally come from film cameras. If a focal length of 24mm is specified, the actual focal length of the digital camera has already been converted. Digital cameras have smaller lenses and therefore a shorter focal length. For example, a digital camera may have an actual focal length range of 5 to 16mm, which would be a super wide angle lens on a film camera, but on digital cameras with their smaller lenses this is equivalent to a 'normal' lens. Nowadays, however, the focal length of the lens is usually given as the converted equivalent of a film camera.