The Zenit-4 ,Zenit-5 and Zenit-6 are all variations of a totally new design, having little or nothing in common with previous designs. The Zenit-4 is a leaf shutter Single Lens Reflex with a built in light meter and interchangeable prism. The Zenit-4 can be operated manually or in a semiautomatic manner. The Speeds and f stops are mechanically interlocked so that changing one automatically changes the other. The camera is covered with black nylon fabric. All controls on the front of the camera are on the lens mount. Lens mount is the same as the Voigtlander Bessamatic and all lenses are interchangeable. Engraved on the upper right of the camera is "ZENIT-4" in Cyrillic script or English block letters. Centered over the lens is the selenium photocell (source: http://www.commiecameras.com).