The Focal length reference article from the English Wikipedia on 24-Apr-2004
(provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Focal length

For thoughtful child sponsors

The focal length of a lens is the distance from the lens to the focus.

Normal lens

Telephoto lens

Wide angle lens

This is the "Focal length" reference article from the English Wikipedia. All text is available under the terms of the GNU Free Documentation License. See also our Disclaimer.