rear curtain flash sync for leaf shutter

**ctbrownmass** · 14-Jul-2006, 19:31

there is a circuit design to make a lf shutter fire a flash at the end of the shutter time, sometimes called rear curtain flash sync. this circuit has a delay that will ,when conected to the pc cord delay the flash sync from fireing the flash at the start of the shutter opening to the end. is there any info.on the circuit diagram?

**David A. Goldfarb** · 14-Jul-2006, 20:35

The "rear curtain" is a property of focal plane shutters, but I think you can program a Pocket Wizard to flash at the end of the exposure with a leaf shutter.

**Bob Gentile** · 14-Jul-2006, 21:53

Originally Posted by ctbrownmass

"... is there any info.on the circuit diagram...?'

IIRC, a simple R-C network should do it. A capacitor in series with the PC cord and a resistor in parallel with that. Values are such that resistance (in Ohms) times capacitance (in farads) equals the time delay (in seconds).

The actual amount of delay you need will be determined by the shutter speed. In practical terms, resistors in the K-Ohm range with capacitors in the microfarad range will yield time delays in the millisecond range.