I've seen a few adaptions of the Rodenstock Imagon lens to various medium format cameras. I've never been able to afford one for my rb67, unfortunately, so i think I should just make one. The lens itself is nothing more than a achromatic doublet, from what I've read. If that's the case, all I really need is a shutter/lens mount that will fit on an rb67 and a screw on diopter (and a tube to connect the two, of course), correct? As for the diffusion disks that come with the imagon, I could replace those with a set from mamiya's soft focus lens.

The problem is, I've no idea what I'm doing...
I assume that screw on diopters magnification is related to the focal length, so how does +1.0 or +2.0 translate into focal length? Will I have problems with the image circle being big enough? How do I figure out where infinity focus would be? Most importantly, where can I get a high quality, 2 element diopter?