>>3231279Actually long before that Voigtlander had already figured out a clever if somewhat cumbersome way to make sure there was no film left in the camera when you open it.
Their 60's Vitomatic cameras (and maybe others) use a dual hinge mechanism where you first open a little door that allows you to see the bottom of the film cassette without letting any light leak to the film itself, and only then you can open the rest of the back.
Pic related.
