Originally posted by Wasp It has been a long way down.
There is probably an MBA dissertation in the whole story. My take on it is that the rot set in when Pentax stuck with the M42 mount until the mid seventies.
Around these parts, it's pretty clear Pentax was a hugely successful brand in the '60s and '70s, as you still see a lot of treasured (if not used in a couple of decades) Spotmatics, right from the original through the SP1000 and Spotmatic F. Even the ES models seemed to do well - they certainly seem to have sold better than the Minolta XE-7, but the Nikkormat EL apparently did well too.
What I don't see many of are the original K bodies. I can't think of the last time I saw a K2 or KX in the flesh. They're out there, but nowhere in the numbers of Spotmatics, or ES models. It was obviously painful for Pentax to switch lens mounts from the M42 - which had essentially disintegrated its universality - as several companies had their own take on how to do open-aperture metering.
But they definitely bounced back with the M series bodies. ME's and ME Supers were evidently very big sellers around here - then again, everything SLR sold like hotcakes in the late '70s early '80s.
I would say the "rot" set in with autofocus. Early AF bodies were button-pokey, buzzy affairs, and the Pentax SF series were buzzier and pokier than most. But at least Pentax stayed in the AF SLR game, as others like Konica, Yashica, and Ricoh threw in the towel and turned their efforts to compact point and shoots. It seems clear to me Pentax put their best efforts and best designers into making the compact cameras, as that's where the money was through the 1990s. The PZ series, MZ series, and (ugh!) *ist 35mm series were all a good step and a half behind what Nikon and Canon were doing at the time. At least they weren't Minoltas, which quickly degenerated into a series of SLRs with techie features no one asked for, and consistent reliability issues. RIP Minolta.