Sinar actually did…
Jenoptik, Frank & Heidecke, Leaf and Sinar were the original actors behind the Hy 6. Jenoptik seems to do other things, Frank & Heidecke ceased to exist, but was reborn as DHW, Leaf was acquired by Phase One and Leica bought Sinar.
A quick search on Google come up with this link:
Rollei HY6 MOD1,& MOD2 W/Sinar/Leaf Backs - Photo.net Medium Format Forum
Once the Hy6 was introduced I felt that it was not an optimal choice for MF digital. The main reason was that it is a 6x6 design, while sensor development was more oriented to sub 645. Today, the most modern sensor for MF is 44x33. Hell will freeze to ice before larger sensors arrive, as the two major vendors of MFD backs (Phase and Hasselblad) and both MF DSLR vendors (Pentax and Leica) are comitted to 645 or sub 645 frame sensors.
Now, using a Hasselblad 555 I realize that 6x6 is not a bad thing, but I still lack a real ultra wide. The widest I have is 40 mm, that is something like 24 mm on a DSLR. But, shorter lenses can be made. Pentax has a 25 mm lens.
On the Hasselblad I can turn the back 90 degrees for vertical. Nice because it works with a 45 degree viewfinder. With a normal prism view finder the camera can be used with an L-plate, much easier than messing with a 10-35k digital back.
Leaf had a nice digital back with internal rotation of the sensor, really neat.
Best regards
Erik
The HY6 is the coolest MF SLR on the market, I just wish Phase and Sinar had of adopted it as their SLR platform.