Originally posted by RiceHigh I can say what you guessed is absolutely wrong as there is the counterexample of the *ist D and my TTL Pentax flash guns which were made in the 80s. No issue here, very accurate and consistent even at ISO 400. No problem in total darkness and under daylight outdoor.
If the flash system works flawlessly up to ISO 400, what else do you actually need? To shoot with flash at ISO 1600 ??
I certainly no no problems with thte *istd and TTL. so far as I know Pentax has never explained why they quit supporting the system they had used for 20 years.
Maybe there is a good technical reason, or a good cost reason, or maybe just a intentional reason to force everyone to buy a new flash unit.
Absent any official explanation that passes the laugh test it has been my assumption that
the true reason was the latter. After all they have to make a living and if I keep on using my 20 year old flash, they never will make the living they need.
In fairness to them though it is clear that there are a lot more 'things' going on inside
the digital cameras such as now a likely 'live view' reader, and trying to collect accurate information to feed a flash with all these other things going on might well be increasingly difficult with the increased potential for a 'feed back loop' with the data received controlling the flash, and the flash is controlling the data received