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wendrock Apr 8, 2011 12:52 AM

How should an external flash be sincronised to a digital camera?
I am using a basic digital camera but want to use an external flash. If I fire the flash the same time as the shutter the camera does not see the flash, What delay should I have for it to see the flash?

tizeye Apr 8, 2011 7:31 AM

How basic a digital camera, and what do you mean by "does not see the flash."? How are you firing it now?

A non-hotshoe, non-Pc terminal P&S camera limits options. About the only way to fire off-camera is with an optical trigger attached to the off camera flash. It also requires using the on camera flash to trigger the optical trigger wjich works well unless the camera emmits a pre-flash for metering, which would fire the off-camera before the shutter is actually open.

"Camera does not see the flash" is that not recording EXIF data which reads "no flash". That is actually quite common with remote triggers in manual flash mode. Technically, the camera (and EXIF data) is reading ambient light and the flash simple fills in the shadows with its much shorter burst while the shutter is open. On the other hand, are you talking about shutter sync speeds caused by either the pre-flash premature firing as noted earlier, or a partially darken picture cause by fast shutter speed (i.e. outside sunny day) and the flash firing when the shutter is partially closed.

frank-in-toronto Apr 8, 2011 9:30 AM

i think the op is holding the off-camera flash and pressing the FIRE! button hoping to do a human-sync. as tizeye mentioned, a slave flash will do what you want if your camera doesn't emit a "pre-flash". what camera do you have?

VTphotog Apr 8, 2011 5:21 PM

The easiest way to get this to work is with a 'digital' slave flash.
Digital cameras (and some film cameras) use a 'pre-flash' light pulse to determine exposure. Normal slave flashes will trigger on this pre-flash, and won't expose the picture at all.


Ozzie_Traveller Apr 8, 2011 7:01 PM

G'day Wendrock

Brian above has got it right - no offence to the others above
Tizeye is close, tho I have not found an optical trigger that will work with a slave flash ... they all fire via the 1st flash they 'see'

All P&S cameras and most dSLR cameras using eTTL metering fire the flash multiple times as part of taking a flash photo
The camera fires the 1st time for a metering shot, then the 2nd is the Red Eye reduction shot, then the 3rd shot is the Big One to take the image itself

You need to get your external flash to match 'the big-one' ... and your external flash needs to be a "slave" flash
A Slave flash has a small switch on the back to swap between 'normal' mode to 'slave' mode, and when in 'slave' mode a second slider switch goes beween positions 1-2-3-4

In training the flash, you need to test to see if your camera fires the slave at position 1 or 2 or 3 or 4
Place your new flash on a table and take pictures of it until your camera shows the flash going off


Once you work out which slave-position is needed, then you're right to go using your new flash as an off-camera flash

Regards, Phil

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