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GN Number calculation is for manual flash, right?

StephenStephen Member
edited September 2016 in flash & lighting
I was reading Neil's "On-Camera Flash" 2nd edition.  In the chapter on the GN Number, an equation is presented to help find the distance for correct flash exposure.

GN Number = f-stop x distance

I presume this is for manual flash only, since that is where distance is actually a controlling factor in the flash exposure, correct?  (Power of Flash, Aperture, ISO, Distance between flash and subject)  The text in that section doesn't state explicitly "manual flash."


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