I noticed that Ilford still makes 5" roll film during the ULF special order. except for the fact that you would lose individual sheet processing , would it be useful to have a 5x4/5x7 roll film back like the Horseman 6x9 backs do for 120 film? Probably not but let your mind wander a bit at the possibility. I'm sure arial cameras likely had something but you wouldn't want to hike with it.
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