The Contax G series cameras had autofocus and titanium bodies.They were beautiful cameras -I have one but sadly it is faulty and parts are no longer available.
The G series Zeiss lenses are very good-particularly the 45mm Planar which is reckoned to be one of the sharpest lenses ever made. I do not own a 45mm Planar but I do own a 28mm Biogon and a 90mm Sonnar-both of which are also very highly regarded. Both my lenses are mint and are complete with the original caps and the highly sought after titanium lens hoods.
The Zeiss Contax lenses are great performers and are not difficult to find as hundreds of thousands of Contax G series cameras were sold - particularly in Japan. However do not expect to find them at bargain basement prices.
I bought two adapters to use the Contax lenses on the Sony a7.The adapter is difficult to fit onto the lens so I bought two so to avoid having to move them from lens to lens. If you do not click them right in and get them into exactly the correct registration the lens will fall out of the adapter after you have mounted it onto the camera - not recommended treatment for a prime piece of glass.
A company called Techart makes an adapter which allows you to use the Contax lenses on the Sony a7 with autofocus. However the adapter costs nearly $400 and has had mixed reviews.
The 90mm f2.8 Sonnar is great to use wide open and being longer and wider aperture -a much wider aperture- than the lens on my Leica X Vario gives a totally different effect and colour rendition. Here are two photos taken with the 90mm Sonnar .The first is one of my grandaughters,Scarlett.The second is of a sleepy lady,Phoebe.