Thoughts on Trailing Curtain Sync

John Sessoms jsessoms002 at
Fri Jul 2 16:53:47 EDT 2010

The K-10D and K-20D both allow you to set the on-board flash to trailing 
curtain sync. How difficult would it be for them to make the hot-shoe 
also fire on the trailing curtain when a non-dedicated "flash" is 

E.G. like with a radio-sync transmitter or Vivitar 285HV? Dedicated 
flash like the AF-540FGZ has its own circuitry to talk to the camera and 
can be set to trailing curtain sync.

Is this something they could do with a firmware update?

Or is it something that would require radical hardware revision?

For that matter what do the dedicated pins on the Pentax shoe tell the 
flash? I know what the big one in the center does, and it's obvious 
which one is ground.

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