Originally posted by biz-engineer ... There must be some identifiable causes for the slide down to be consistent over a two decades long period.
Well - at least in Europe the slide down was consistent for more than 4 decades. And there is a number of good reasons for it:
1. Asahi Optical had always been a company with R&D guys who followed their own belief rather than market demand. Many times they were the first to come up with something but failed to benefit from being the first.
2. By 1976 Asahi Optical was the last of the Japanese major brands to give up the M42 mount, when everyone else had realized that bayonet is faster and more suited for communication between lens and camera.
3. Although Asahi was the first to offer an autofocus system (ME-F), they fell behind when Canon and Minolta came with a radical, new AF-centered approach in the late 1980ies. Pentax's AF always was too conservative, rather slow and definitely not on par with Canon's ring motor solutions.
4. In 2001 desaster started to unfold: Ashai had been the first to present a 24x36mm DSLR. However, the Philips sensor failed to provide the image quality that was required at the high price-point. So they had to pull the emergency brake and go for APS-C.
5. When the *ist-D finally appeared on the market in 2003 it was a nice camera, undoubtedly superior to any other APS-C offering at that time. But how would you be able to catch up on lost market shares by offering a camera that is almost twice the price of your competitor(s)?
6. Whatever happened in the years since then, it was too little, too late.
There is one more aspect to it:
While Asahi and Olympus were camera companies that tried their luck in medical technology, Canon, Minolta, Ricoh, Konishiroku (Konica) and Kyocera (Yashica) became extremely successfuly in printing and copying technology. Canon soon became a universal and quite independent high-tech company with their own semiconductor development branch. Long story short, by 2000 everyone else was significantly larger than Asahi Optical and obviously had more money to spend on R&D as well as marketing.