In photography, the distance that a lens must be moved in order to focus a sharp image on the light-sensitive film at the back of the camera. The lens is moved away from the film to focus the image of closer objects. The focusing distance is often marked on a scale around the lens; however, some cameras now have an automatic focusing (autofocus) mechanism that uses an electric motor to move the lens.

1. To become focussed or come into focus
2. To put into focus.
3. To put into focus; as of an image on a screen; SYN. sharpen.

See Federation on Computing in the United States.

In television and raster-scan displays, to make an electron beam converge at a single point on the inner surface of the screen.