Zeiss Ikon Box Tengor 54/2
The larger metal tab on the top left is the shutter release, and the shorter one on the right is lifted for long exposures. Most other versions of this camera have the shutter release on the side near the lock button. At the top are two viewfinder windows. Above the lens is the focus control: Infinity - 8m, 8m-2m, 2m-1m. Next is the lens with its distinctive mirror shutter. At the bottom is the aperture selector.