Originally Posted by Lowell Goudge
As an observation on RiceHigh's posting regarding the AF540FGZ and TTL on the *istD,
I have very successfully used the 540 on my *istD with K mount lenses in TTL mode. In fact the flash automatically selects TTL mode with K mount lenses.
I have tried taking a KAF2 lens out of automatic apature mode, but TTL is not available.
Clearly this is a function of the lens mounted on the camera, not only the flash.
Perhaps you could ask pentax for a software change, for flash mode, to allow selection on the camera of M, A, TTL, or P-TTL. Presently other modes are accessible by pressing the red-eye button on the top of the camera, and the change could be either here, or as a new function
P-TTL need focusing distance information for the calculation of flash exposure. So, P-TTL is never possible with K and A lenses which lacks this essential info.
However, with F lens or later, Pentax should let the *ist D or DS users to choose which mode they wish to use as the 360 and 540 are actually TTL capable. Anyway, the TTL auto flash for Pentax is already a real past tense.