The Olympus OM Zuiko Auto-Zoom 35-70mm f4 Auto Focus lens is a fascinating artifact of the early autofocus days: a self-contained autofocusing lens with sensors, batteries, and motor in the standard OM mount. Peer into the lensmount side and you can see the fixed prism that directs part of the light to the AF sensors. It's not fast focusing, but it does work. They were doing their best! If you've ever dreamed of an autofocus OM-1, this is the lens for you. In excellent condition, with a working AF system. Requires three AAA batteries (not included)