Quote Originally Posted by Ian Grant View Post
The KW made Praktina had a direct view finder which was later copied by Pentax with the Asahiflex 1 (their first SLR) I'd guess this is being muddled with a rangefinder.

Most early SLR's had to be stopped down manually to the working aperture after focussing so the direct finder gave an alternative bright way of framing. It was the lack of instant return mirrors, no preset aperture stop down, which made early SLR's less easy to use. Even early Pentax cameras were poor in this respect.

It would be interesting to list what cameras etc were released around 1958 because that's the watershed when Pentax brought out the first of their modern Asahi Pentax SLR's with semi-auto aperture control, instant return mirror, better Pentaprism and shutter speeds, that's mirrored by other Japanese manufacturers like Minolta with the SR-2, Nikon joining them a year later.

So the OP's right to highlight 1958 as a key fime of change.

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.