Z10, SFX and SF7 have that 3rd Digital pin too AFAICT 2007/10/19, John Sessoms <[EMAIL PROTECTED]>: > From: "Bob Blakely" > > > I'm curious. What can the flash know of rear curtain sync timing save > > that given it by the camera's shutter? If nothing, what's to set on > > the flash? What difference could it possibly make? > > > This is just a guess, but I know the AF-500FTZ has a switch position for > rear curtain sync. > > What I think is somewhere in Pentax's dedicated flash connection, > there's a pin that gets a signal (V+ or ground??) when the shutter > curtain opens and loses that signal when the rear curtain starts to > close. Say something like this: > > Curtain Curtain > |Opens |Closes > __------------___________ V+ > > OR > > --____________----------- ground > > It'd be easy to build a trigger circuit to detect the state changes and > switch the flash trigger to either the leading edge change or the > trailing edge change. > > Thinking about it now, a standard hot shoe could just go to ground for > the duration of the curtain being open, so you don't even need the > dedicated pin to trigger rear curtain sync; just design your rear > curtain trigger circuit so it will flash when the ground circuit opens > again. > > For a lark, I tried the AF-500FTZ with a K-1000, and it doesn't do rear > curtain sync even with the flash switch set in rear curtain position, so > I think Pentax does use a dedicated pin. > > And, I'll bet it's the 4th pin in approximately the 2 o'clock position > that permits rear curtain sync, since Pentax had TTL Auto-flash with the > LX and Super Program and AF-280T, which I'm pretty sure uses the two > additional pins at 5 o'clock and 7 o'clock. > > The AF-500FTZ manual says rear curtain sync only works with the PZ-1 > [PZ-1P], which I expect was the only camera with that 4th dedicated pin > at the time the manual was written, because AF-500FTZ rear curtain sync > does also work with the *ist-D. > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. >
-- Thibault Massart aka Thibouille ---------------------- K10D,Z1,SuperA,KX,MX, P30t and KR-10x ;) ... -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
