I'd like to use a newer Mamiya 6 with off-camera studio electronic flash and a long exposure for ambient light to cause a dark outline around a moving subject. I'd also like the flash to simulate the effect of a rear curtain focal-plane shutter flash synch freezing the action towards the end of the exposure rather than the point where the leaf shutter is first fully open. I think the ambient exposure would be on the order of 1 to 1/4 second.
Is there some sort of commercially available gizmo that would allow me to do this?
Joe