[Klaus]

I had the mk2 version of that adapter but returned it because focus was not so accurate with the a7r.

I had the G21, G28, G35, and G45 in the past and the G90 is in front of my eyes now. I can assure you that the aperture is purely mechanical but with electronic contacts to provide EXIF.

Unfortunately, like many Leica M lenses, the Contax G lenses don't work that well on the Sony A7 series, except the G90.

G21 & G28 Biogons suffer from heavy color shift and corner smearing. I used them only with macro tubes.

G35 & G45 Planars are good from 5.6 onwards but at larger apertures, only the center was sharp.

 

Oh, I see, I stay corrected then :-)

Thanks for the info - I was almost considering to try it. But I reckon the Loxias are a better idea after all.

There are also rumors about a 18mm Batis.