format was Nikon 's 1961 f/3.5 PC-Nikkor. It was followed by an f/2.8 35 mm PC-Nikkor and an f/3.5 28 mm PC-Nikkor. Other manufacturers, including Olympus , Pentax , Schneider Kreuznach (produced as well for Leica ), and Minolta , made their own versions of PC lenses. Olympus produced a 35