Hello I just picked up a cheap Hasselblad 500/C (C/M I think) with an old C-12 back on it (you know, the one with the peep-hole.) The problem is, the little peep-hole door is very loose, and pops open quite easily. If that door opens mid-shooting, will it expose the 120 film to light? Maybe I'm being stupid/naive here, but I was thinking the backing paper would keep that from happening. Is it safe, or should I avoid that happening? I won't be able to pick up a modern back for a while, so I'm using this setup for the time being.