Carol, You probably heard about Contax G1/G2 Rangefinder camera series. They used special G-mount with autofocus. Contax G1/G2 RF mount has quite short flange focal distance of 29 mm so it could not be used with any DSLR :( For Hologon especially back focal distance is extremlly short (6.8mm) so It is told that Hologon isn't compatibile with current digital sensor. I could use any Contax-G/Nex adapter (I choose Kippon one, which is most pricely but I didn't wanted to get any bad surprises), but to save my sensor I had to crop a little protective horns from rear side of lens. I may send You some final photos of Hologon's rear cut off, if You wish :)

It is trully amazing with geometry, sharpness..only magenta colour shift (at corners) and vignetting is a little bit problem.
Thanks again for Your attention and comment, best regards, WZ.