Another very useful adapter is the Fotodiox Pro Contax/Yashica to GFX - pictured below is a Zeiss 100mm f2 Planar which marries very well with the GFX 50S.

Although the lens is no lightweight, it balances very nicely with the camera. The fit for both mounts is excellent - no hint of play at all and infinity focus is guaranteed. I know of a few GFX users that have used this adapter with the ever popular Contax Zeiss 85mm f1.4 Planar. As there are are no electronic connections, unlike the Fringer adapter for Contax 645 lenses, this is manual focus only.

Although the lens is no lightweight, it balances very nicely with the camera. The fit for both mounts is excellent - no hint of play at all and infinity focus is guaranteed. I know of a few GFX users that have used this adapter with the ever popular Contax Zeiss 85mm f1.4 Planar. As there are are no electronic connections, unlike the Fringer adapter for Contax 645 lenses, this is manual focus only.