The Olympus Pen F was the world's first and only half-frame system single-lens reflex camera, released in 1963. The Olympus Pen F was a revolutionary camera packed with innovative features. With the new digital PEN cameras Olympus started a new era of mirrorless cameras with outstanding design. The lens cap with the special F logo has a diameter of 37mm and can be used with the M.ZUIKO DIGITAL 17mm 1:2.8 Pancake lens.