The Pentax LX is a classic 35mm film SLR camera that was introduced in 1980 to commemorate the 60th anniversary of Asahi Optical Co. (hence the Roman numerals LX). It was the top-of-the-line professional camera in the Pentax manual focus range, with manual and aperture priority automatic exposure modes and an advanced light metering system. The LX uses the K mount, which is the Pentax proprietary bayonet lens mount, and has a large body of accessories. The camera has an uncommon frame counter, being able to keep track of the frame number in either direction, whether advancing or rewinding the film. This feature aids in taking random-access multiple exposures anywhere along the film strip.