I am thinking of upgrading to a Leica M series camera and wanted to know how compatible these Cassettes might be--I heard they work with some M series cameras but not others. Does anyone happen to have an answer to my question?
I have never seen one of these in person, but if I understand the design correctly they are not compatible with any M series camera as they are designed to be opened by cameras with a pull-up rewind mechanism as in most manual rewind SLRs.
They're useful if you want to bulk load your film. You can open the light trap by using the film rewind knob. They're a well machined piece of equipment. I got mine from a garage sale in a box full of photo accessories. I think they're made in England.