I finally bought the adapter and I want to warn all of you that it is only crap.
The desire of all of us who own beautiful Contax 645 lenses to finally use them will remain once again a dream.
The first time I mounted my 80 mm on my nikon D3 I couldn't believe to my eyes! Finally I can use it!
But after few shots i realize which is the problem: the diafragm have to be located in the focal center of the lens. If we put the diafragm in another location the lent won't work properly.
In fact we use the diafragm to have more depth of field, but the adapter diafragm just block the images after the focal point. So a diafragm located between the lens and the camera is not only useless but it affects the image creating a black ring . It is like using a nikon Dx lens in a full frame camera, you just miss a part of the image.
So with this adapter you can use your Contax Zeiss 645 lenses but only at full aperture.
My adapter also had a problem on the release leverage, so to detach it from my zeiss lens I had to use a screwdrive and open it.
Fortunately the shop accepted the return and gave me back the money.