For many years, a fixed focal length (prime) 50mm lens was standard for film SLRs. Although 50mm lenses are not nearly as popular as they used to be, there are still many people who want one of these in their kit.

Canon's 50mm f/1.2 in Leica screwmount (39mm x 26 tpi) is something of a legend. Introduced in 1957/58, it is very fast and today it is relatively affordable. The main alternatives, after all, are either Leica Noctiluxes (the 50mm f/1.2, 1966, discontinued, or the 50mm f/1, 1967, still current) or...