Minolta introduced their manual focus lens mount in 1958 with the SR-2. The mount would be called a few things over its 40 year production run, including SR and ”Minolta Mount” but is now generally known as Minolta MD. There were four versions of the SR/MD lenses over the years, but all retained basic compatibility with each other. This gave Minolta MD bodies a huge library of lenses to choose from without worrying about the compatibility issues that plague some Nikon and Pentax cameras. Minolta lenses were some of the first to feature multiple coatings and benefited from Minolta producing and shaping their own optical glass, which was uncommon at the time.