Originally posted by Elroy Jetson Pros shot Nikon and Canon was not popular. The big discussion back in the late 60s was whether it was better to stick with the M42 screw thread mount or if the 'other guys' were onto something with bayonet mounts.
You are absolutely correct regarding Canon. The optics were respected but people were suspicious of the breech-lock mount and the late-60s Pellix (stationary, half-silvered mirror) camera line did not help things. Topcon was as popular, if not more so, as Canon. I was actively camera shopping in 1970 and don't remember seeing Canon on the shelves at any of the camera stores. In fact, the first time I saw a Canon camera was in the Fall of 1969 when a family friend was showing us his new camera. It was not until the development of the AE-1 (1976) that Canon gained market share. The camera was sophisticated and inexpensive compared to similar models offered by the competition. With the AE-1 Program and A-1 cameras, Canon finally rose to 1st tier rank.
I also remember the M42 vs. bayonet discussions. M42 fans claimed that bayonet mounts were prone to wear and were overly proprietary, driving lens prices up. Bayonet fans claimed (rightly) that M42 was slow to mount and had risk of cross-threading (possible, I guess). They also made the claim that M42 stop-down metering was inherently more accurate. In the end, the bayonet mounts won due mostly to the sophistication of coupling that is possible when the lens always has the same fixed orientation.
Is for me and my camera purchase, I bought into the stop-down metering logic and really wanted a Pentax. Unfortunately, I did not have the money and was shopping for Mamiya or possibly Yashica instead. I ended up with a Ricoh Singlex TLS which served me very nicely for the next 15 years or so.
Steve