How about custom made? I use sinar 140x140 frame and DB shutter and flexadapter and leaf back combinations. It has similar to capture group true wide version. If you use sinar system, it is very cheaper one. I use H1 with hc 50-110 & 150, for wideangle, I use custom sinar setup, pentax 35 for 645, nikkor 28 PC, sigma 12-24.