Hi John,
I think it could be done in _software_ to make it work for any flash,
but it would require a bit complicated menu to give the camera the
required information about P-TLL or "center contact only" or expected
burn time.
In the Z-1 time I measured burntime of several flashes at hand, they all
were much faster than the 1ms mentioned by Adam. It requires additional
measures in the design to increase the burntime, I have seen that some
Metz designs have that.
It could also be in _Hardware_:
In the past I measured the trigger pulse of my (P)Z-1 (Pentax hi end
35mm camera).
The trailing edge of the trigger pulse was the right timing information
for the rear curtain sync.
So the pulse width of the triggerpulse changed with shutterspeed.
And on the flash the decission could be for first or second curtain sync.
I made even a small interface circuit to get rear curtain sync with non
dedicated flashes.
I donot know if my K20 has the same info in the rear sync. I think it
would not harm other use if it was there.
When I'll be retired, I might find time to measure this.
Groeten, Jos
John Sessoms wrote:
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 installed?
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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