Quote Originally Posted by Dr Croubie View Post
It could work in the same way as the SWC, no mirror. If it was made for NASA it was probably made for either astronauts taking shots of earth from space, or taking night-shots of skies. Either way, it could have been built as an aerial camera, fixed hyperfocal so no need to focus.
I did not refer to the mirror (maybe the mirror-lock up will not release automatically after exposure, I don't know), but to that 4mm to contain the distance from film to shutter and the shutter itself.