The original Riga-made Minox had a brass chassis covered in a stainless steel shell, which telescopes to reveal or cover the lens and viewfinder windows, as well as to advance the film. It was equipped with a parallax correcting viewfinder, which was coupled to a Cooke triplet type Minostigmat 15 mm f/3.5 lens. The lens was capable of focusing as close as 20 cm, and, due to its small image size, provided such depth of field at full aperture that a diaphragm was deemed unnecessary. The maximum focus zone was about one meter to infinity. In front of the lens was a metal foil curtain shutter, which was itself protected by a window. These were advanced features at the time for any camera, regardless of size.