Minolta SR-mount - Wikipedia, the free encyclopedia
MD - In 1977, the XD series introduced an additional tab on the lens which reported the smallest available aperture (f/16, f/22, or f/32) to the camera to accomplish shutter priority automatic exposure in S mode on the Minolta XD-7 (XD-11 in the U.S.A.), and later in the P (programmed automatic exposure) mode on the X-700. The proper use of this feature meant that the lenses had to be set to their smallest aperture. In 1981, MD lenses included a minimum aperture lock that prevented the aperture ring from accidentally being moved.
There are also adapters for Minolta/Sony A-mount cameras, but they either do not maintain infinity focus or contain glass-elements, working as 1.2-2× tele-converter, changing the optical properties of the system and often deteriorating the image-quality.