Here's an interesting problem. I want to mount two small cameras (Panasonic GH1) on a minimal rig so that I can shoot simultaneously with them. Unlike 3D video, I want the lenses to be as coincident as possible. Geometrically, I think the best way would be to mount one camera on top of the other, but upside down. I might also use a tilt adapter on each so as to compensate a for the offset. Not sure what minimal hardware I need for this. Any advice?