These cameras used the "C/Y" lens mount, short for "Contax/Yashica": Yashica being the lower-end consumer brand SLR system made by Yashica/Kyocera that shared its lens mount with Contax SLRs. Zeiss lenses in the C/Y mount came in either AE or MM varieties. MM lenses were more recent, with a setting that allowed the camera to select the aperture as part of its autoexposure system, while the older AE lenses did not. There was often no difference between an older AE and a newer MM lens apart from this feature. Sometimes, the older AE lens may be worth more on the used market because it may be a Germany-made example, while the newer lens may be Japan-made, despite their optical formula and build quality being identical.