1) An autofocus camera 2) Olympus option 3) Optical device 4) Photography equipment 
An autofocus (or AF) optical system uses a sensor, a control system and a motor or tunable optical element to focus fully automatic or on a manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system has to be done manually until indication. Autofocus methods are distinguished...
(from the article `photography, technology of`) Some cameras evaluate the coincidence (or lack thereof) between two rangefinder images by image analysis with a microchip system. This signals ...
(Film cameras) The camera's ability to automatically focus on the subject to be photographed.
autofocus Having the ability to focus automatically; such as, an autofocus lens or an autofocus camera.
noun an optical device for focussing a camera or other instrument automatically
having the ability to focus automatically: an autofocus lens; an autofocus camera.