The Contax / Yashica mount was the result of a collaboration between Carl Zeiss and Yashica after the latter purchased the rights to the Contax name in 1975. The goal was to merge Zeiss’s excellent lens design with Yashica’s electronics and manufactering process within a single mount. This came only a few years after Leica began collaborating with Minolta.
Both Yashica and Contax would produce cameras and lenses for this new mount, with Yashica targeting consumers and Contax aiming at professionals. Contax SLRs were known for pushing the limits of electronics at the time, and for producing some of the best lenses Zeiss designers ever came up with.