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Posted by Doug Clifford on April 03, 2002 at 09:20:59:
In Reply to: Flash sync with Digital Camera posted by Reza on April 02, 2002 at 01:34:47:
: My external flash arrangement does not sync while using a digital camera. Is this a common problem with digital cameras?
John is entirely correct -- when a built-in flash on the digital camera is set for red-eye reduction, the short pre-flash can cause external flash units to fire prematurely. However simply turning off the red-eye reduction will not solve the problem for many digital cameras.
Many digital cameras always fire a pre-flash just micro-seconds before the main flash. The pre-flash is used to set the white balance before the picture is taken. This pre-flash will also trigger any slaved external flash units, thus rendering them useless.
The following digital cameras don't fire a pre-flash
to set the white balance:
Nikon Coolpix 900 series digital cameras and all Kodak, Sony,
Ricoh, Fuji, Casio and Hewlett-Packard digital cameras.
The following brands determine the white balance by
firing a pre-flash:
Olympus, Agfa, Epson, Nikon Coolpix 700 and 800 series models,
Canon, Polaroid, Panasonic PV-SD4090, Toshiba TDR-M60 and the
Pentax E1-200.
This second group of cameras require special flash units, or delaying triggers, in order to use them with external flash units. The source for this information is SR Inc., mentioned in the next paragraph.
Solutions:
SR Inc. makes several models of Digi-Slave flash units for
digital cameras, including a ring flash model for
macro-photography. There's also a more detailed explanation of
the pre-flash problem on their home page. Go to http://www.srelectronics.com/
Here's an article on "Disabling the Olympus FL-40 Pre Flash" when used with an Olympus digital camera. http://davidweikel.com/E10_samples/preflash/preflash.shtml
"Using a Slave Flash" ( http://www.leesoft.com/d600l/2/2.7.html ) Although this is part of the Olympus digital camera FAQ, this page deals with the problems people have using slave flash units which prematurely fire when triggered by the digital camera pre-flash. Offers some homemade schematics to design your own flash delay circuit.
Another Issue:
Be aware it is very risky to use an old flash unit from the
1980's and early 90's on any digital camera or 35mm autofocus
SLR. The trigger voltage on old flash units can be hundreds of
volts, enough to fry the electronic circuitry of your nice new
camera, or cause pitting of the electronic connections which will
eventually lead to camera failure and expensive $$$ repair bills.
The safe flash trigger voltage for new cameras is 12 volts for all brands except Canon. Canon cameras should only be used with flash units which have a trigger voltage of no more than 6 volts.
If you wish to use an old flash unit with new digital cameras, you will need to buy a Wein Safe-Synch module (which reduces the voltage down to safe levels. ( source http://www.tiffen.com/ ) Paramount Cords also makes a voltage-protected synch cord for Nikon Coolpix digital cameras ( source http://www.paramountcords.com )
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