Why are my studio pictures dark when I use a slave flash

John writes:

Hi DIYPhotography,
I am using a D70 for my studio shots, and one external optical slave flash.  When I take a picture, the internal flash shoots, and triggers the external flash, and yet my pictures are dark.
Can you help me?


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This is what DIYPhotography.net has to answer

Hi John,

I do not know your entire setup, buy my guess is that your internal flash unit is set on iTTL.

When the flash is set to iTTL it shoots a short pre-flash to measure the strength of the flash needed for the shot. That pre-flash is done before the curtain opens. After the curtain opens, a stronger strobe is shot. And here is the catch, when the main strobe triggers your slave, the slave is uncharged, after the pre-flash discharge.

Here is what you can do to override the problem. Set your internal flash unit to manual at 1/16th of its strength. Now, place a small paper between the flash and camera body, so the internal flash will have a lowest impact on the final picture as possible.



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