Do they? I think most modern TTL flash is done via a pre-flash measured by the mirror down TTL sensor which sets the flash exposure, then the regular flash exposure is done. In other words while it is TTL, it is not OTF at all. (I do admit never owning a modern camera however.)
I'm not sure with other brands, but at least more or less all my Pentax cameras support it (well okay, The Spotmatic and ME-Super don't :)
If they didn't, then they would not work with TTL style flashes (ie anything except the 360FGZ) in TTL mode. My MZ-3 certainly works, admittedly thats the newest film camera I have, perhaps the MZ-S does not? Though I'd be surprised.
The *istD also does, given that it supports TTL flash (how well it actually works is another matter...), and indeed there is a sensor in the bottom under the mirror.
Love, Light and Peace, - Peter Loveday Director of Development, eyeon Software
