I have a 4x5 roll film back for 120 film at 6x7cm. Has anyone tried this with their Zero45? Using it at 25mm would lose a lot of the vignetting and be a modest wide angle; using it at 75mm would approximate a standard focal length on 4x5 film...
There is only one way you can answer this, try it and see how you get on
Rae used a 6x9 RFB at first - Since then I have lent her 6x9" back to a friend in Perth to try with his 5x4" Zero - The 120 back gives a more suitable angle of view for her work, but I experienced the problem that 5x4" is about as small I like to contact print her images (In my role as her darkroom boy)
haven't got any 4 by 4 roll film backs, but i can't imagine why one wouldn't work -- as long as you can get it to stay in place. I've been using Grafmatic backs with mine -- make changing film between shots much easier.