JackM: Great, but... should we wait for more lenses for the a7/r, which won't be usable with this sensor, or should we wait for this system? Argh.
I don't get why it would work only for fixed focus. Imaging on a flat surface is a big challenge. Simple lenses have curved image field. There is probably an optimal curvature for let's say 50 mm that will result in a simplified 50 mm design. I'm convinced designing a 20 mm for this non-optimal sensor curvature will still be easier than doing it for a flat sensor.
I second the need for a fast and basic 22 mm lens!