well the question is just academic now. I didn't realize that Tucker mounted the plungercam onto a Hasselblad 202FA. It has a focal plane shutter--the Bronica doesn't. When you take an exposure with no lens on the mirror just flips up and doesn't come back down until you advance the frame. So it's not easily possible to do this w/o a focal plane shutter, so I might try to do this with my old 35mm minolta. But as I wanted the larger neg in square format I ordered a holga (hey only $16 and probably cheaper than my plungercam and I already have the gaff tape) to try out first.