Hi, I'm new to APUG, so I'm not sure whether this is the correct forum for my query, but here goes: I've just bought a 1930s Zeiss Ikon Ikonta A for 120 roll film, and I'm concerned that the red number windows, which have no shutters on this model, may cause problems with panchromatic film. Are there any makes of 120 panchromatic roll film with sufficiently opaque backing paper to avoid this problem? I don't want to modify the camera. Thank you!