I agree, it's impossible that this is fogging. I too have never seen anything like it. It looks like a test strip on a darkroom print. It certainly has nothing to do w/ the red window....you don't even need anything back there, as 120 film has backing paper. I've pried the red windows out of many old folders when they got so dark w/ age that I could not see the film numbers through them, and simply had an open hole back there (w/ a bit of black tape over it when I wasn't checking it). No issues whatsoever.
Maybe there's a light leak somewhere, and that's the creases in the bellows folds we're seeing.
Last edited by momus; 10-04-2013 at 08:34 PM. Click to view previous post history.