Originally posted by adwb Am I correct in thinking that rear curtain sync only works when a dedicated pentax flash is attached directly to the hot shoe?
The reason I ask is that works with the pop up fill flash, but with a dedicated Pentax Metz 48 flash it does not unless the fash its self I set to rear curtain.
No, the Pentax AF540FGZ needs to be set to trailing curtain sync just like your Metz. You don't have to change the setting on the camera (see below) with the AF540FGZ; it only seems to apply to the on-board flash.
Originally posted by adwb With a remote trigger fitted it certainly does not work , Easily proved in a dark room with overly long exposure time set.
There is some communication going on between flash and camera. Switching only the AF540FGZ (in hotshoe) to 2nd curtain sync and leaving the camera on 1st curtain sync will result in 2nd curtain sync triggering (tested on a K-5); it also works on the K100D that does not have an option for 2nd curtain sync in the flash options.
Your radio trigger does not allow that communication.
According to the manuals (not tested), 2nd curtain sync is possible with a remote flash when using the on-board flash (I'm aware that that might not always be a desired option); the on-board flash is even triggered on 2nd curtain. I have no idea how that is supposed to be communicated (it would indicate that the Pentax wireless protocol is bidirectional); this behaviour is also described in the manuals of the the K-5 and K100D.