I've wanted to on my Fuji. I've definitely used them on my Contax
They are very good, especially the newer models. I forgot all the how all the acronyms work, but the more expensive versions are newer with excellent color and contrast rendering. Substantially different from Leica, but equally as good.
I've read mixed reviews about the adapters typically found on ebay. Contax (Carl Zeiss) use to make the best lenses back in the day, and I always preferred their color warmness over Leica lenses.
I really like my Fotasy adapters. Really well built yet inexpensive.
But I know. Buying stuff from China can be hit or miss and there doesn't seem to be any pattern. Avoid the cheapest of cheap stuff, and you're usually better off.
I use (only) manual focus lenses with my a7 and a7r. Now I prepare 4k resolution images and I am really satisfied.
I have 35 lenses, and I use all of them. Contax-Zeiss are among my favourites (with Leica-R, Meyer Gorlitz but also other ones): I know and I use 18 distagon, 50 1.4, 60 makro-planar (what a game with leitz 60 macro), 85 1.4 (here I prefer the Leitz 80 summilux), 180 Sonnar, 300 tessar. ever a pleasure, great lenses.
I used also the new 55 sonnar f/1.8 for sony, but I prefer the 50 planar Contax....
All the best,
sandro
I have only one autofocus lense for my A7ii (Bâtis 18mm) and 13 MF, mainly Zeiss (2 Loxia, 3 Distagon, Sonnar and the rest, Canon, Hexanon, Yashica and Minolta). And I love it