Olympus Pen F

The Olympus Pen F, Pen FT and Pen FV were very similar half-frame 35 mm single-lens reflex (SLR) cameras with interchangeable lenses produced by Olympus of Japan between 1963-1966 (Pen F), 1966-1972 (Pen FT) and 1967-1970 (Pen FV). The chief difference between them was that the Pen FT had an integrated light meter, while the F and FV did not.

Half frame meant that the camera used a 18×24 mm vertical (portrait) format, producing twice the pictures on a roll of 135 film as the regular 36×24 mm format. The smaller image format also allowed for a smaller camera and lenses, making the Pen F system one of the smallest SLR systems ever made; the Pentax Auto 110 was smaller, but with a much more limited range of lenses and accessories, and smaller 110 film.

These cameras were somewhat exceptional since they used a rotary focal-plane shutter, rather than the two-curtain focal-plane shutter commonly used in other SLRs. Since this one-piece shutter opens fully before it starts to close, it can synchronize to electronic flash at all shutter speeds.

Pen-F series cameras are occasionally modified to mount standard motion picture camera lenses for use as film test cameras with 35mm motion picture films. The Pen-F frame size is close to the 35mm motion picture Super 35 frame.