I hadn't thought of it in the past, but I also think the Bronica S series would be good. It can accept a wide variety of lenses. One could easily have a "lens-board" made that would screw into threads purposely made available for this purpose where lenses connect to the camera's bayonet mount system. It has the focal plane shutter, but one could then also use a lens with a between the lens shutter. As someone else pointed out, the Type II bellows has some movements.
A potential problem is the "violence" with which the shutter on these cameras exposes the film when using lenses without shutters. There's no mirror lockup with this camera. But, I would think this could be mitigated by strong support and by the fact that macro requires long exposures. The time period during which the shutter opens is very small, when compared to the overall exposure. Plus, I've used an S2a for years, and I get very sharp photos. This would not be an issue when using between the lens shutters.
By the way, what's the advantage of the focal plane shutter, other than this would make it possible to use a wider variety of lenses?
I am jumping in late,but there is no medium format camera which will do closeups like the Rollei SL 66. Since all lenses can be mounted in a reversed position it can be used amazingly close.
There were no MP3 players available. Dig the flash connector. See the designer here
I can't agree more. The above shot is a mushroom, about 1/2 inch in diameter which I captured on Efke 25 with my SL66 and the 50/4 Distagon HFT lens in the reversed position.
I will say this - medium format macros are not for the feint-hearted. You have next to no depth of field available and limited (SL66) or no movements. In the field, you find yourself stopping down even more than with 35mm, meaning subject movement is often a problem. In summary, your technique has to be absolutely perfect to pull it off.
I have a Rodenstock Ysaron 1:4.5 150mm lens mounted in a a self cocking Copal Shutter with a ring flash. The whole mess is mounted on a Sinar lens board that I use on my Sinar F2. I only mention it because the self cocking shutter may be a good solution to use with your enlarging lenses and you wouldn't have to use a focal plane shutter. You would still have to manually stop down your lens of course.