The Pen series is a family of half-frame cameras made by Olympus from 1959 to the beginning of the 1980s. Aside from the Pen F series of half-frame SLRs, they are fixed-lens viewfinder cameras.The original Pen is a very compact half-frame camera, with just a viewfinder, no meter and fully manual settings. It has a 28mm f/3.5 Zuiko lens. Its shutter settings are 25, 50, 100, 200, B; its aperture range from 3.5 to 22. The back is removed completely for film loading and unloading. The Pen S is almost the same camera, with the following shutter settings: 8, 15, 30, 60, 125, 250, B. It existed in two versions, with a 30mm f/2.8 lens or a 28mm f/3.5 lens. NOTE: Slow shutter speed at 1/2, 1/4 and 1/8.