Completed
195g, MFD=0.19m (same as Flektogon 20/2.8 and Prakticar 28/2.4's)
Yeah, very smooth focusing and joy to use it with my Sony NEX-5. :)

With Sony a7 the results are not always great, due to corner smearing and colour shift.
Now you can use "front end filter" to reduce the astigmatism and the field curvature: >
http://phillipreeve.net/blog/rangefinder-wide-angle-lenses-on-a7-cameras-problems-and-solutions/#Solution_3_Front_end_filter_mod