Focusing on a single year or single innovation doesn't help much in understanding how change unfolded. Among the key innovations was marketing--something the Japanese and mostly American agencies had to puzzle out quickly in the late 50s-early 60s. Nikon arguably overshadowed and helped the SLR competition with its huge aspirational cachet, thanks to growing popularity among pro shooters--something Pentax and Minolta just didn't have. The watershed metaphor is a bit misleading.
Originally Posted by Ian Grant