TTL flash requires a second exposure sensor in the mirror box. P-TTL does not. Pentax drops an "unreliable" feature and saves money. (P-TTL is more or less a software enhancement as opposed to a physical feature. In keeping with current trends most extra "features" seem to implemented in software if that can be done without a hardware change). If it becomes possible to read exposure from the actual imaging sensor in real time I expect that TTL may make a comeback, since it would be a software change.
Pancho Hasselbach wrote: > Hi Bruce, > > TTL works on my *istDS to my satisfaction, by now, with those old > flashes I have. > I have a flash meter and know how to use it, but I think this would not > be wedding proof, e.g. Setting a flash to auto is OK too, the K100D I > owned for a short ime even transmitted the f-stop to my Metz 40MZ-2. > But then, with auto flash and preset f-stop, my KX does the job as well > - or my RB67, with 1/400 sync time ;-) > > So why drop TTL for those who own old flashes, if it is apparently > possible to implement both, at a not so high expense, I guess. > > I always believe there is a conspiracy, if things are not going the way > I want... > > Pancho > > Bruce Dayton schrieb: > >> Hello Pancho, >> >> My understanding of the move by all camera manufacturers away from TTL >> is that the reflectivity of the sensor/filter in front of it, made it >> problematic at best to read from that surface. Every manufacturer has >> found it necessary to pre-flash and read to set proper exposure rather >> than meter on the surface during exposure. If my *istD was any >> indicator, the Old TTL system was not too good. I don't think there >> was any major conspiracy to force us to buy new flashes. >> >> Nikon has been even worse going from TTL to D-TTL to I-TTL. So >> incomparability is even a bigger problem - especially if you had a >> flash for the middle version. >> >> > > -- Entropy Seminar: The results of a five yeer studee ntu the sekend lw uf thurmodynamiks aand itz inevibl fxt hon shewb rt nslpn raq liot. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
