i recently added an sb700 to my d3200 and am unsure how to determine proper amount of power to use in photos.

in another thread here on stack exchange, it was suggested that the ttl metering makes a distinction between two main situations 1) where the speedlight is being used as the main light source, and in which case shutter speed is irrelevant. 2) where the speedlight is being used as fill flash, and shutter speed is relevent.

i shoot in manual mode without the flash and would also like to shoot manual on the flash, so i am unsure if i should just be trying and erroring? should i meter my scene underexposed and than try to balance with the speedlight, and checking for accuracy of this with my histogram? or is there a more precise way of determining how much flash to use?

  • i understand the use of the guide number as it provides a relationship between an aperture and the flashes effective distance; GN=AXD. for example a flash with a GN=36m with a subject 4.5m away means you should shoot at f/8. – user74091 Oct 6 '14 at 13:42
  • but my question still remains, after i calculated my subject distance or aperture with my GN, now how do i determine how much power for my flash to use? 1/1? 1/4? 1/128? – user74091 Oct 6 '14 at 13:43

With manual flash and camera in manual mode, I think you already hit on one method of "metering" ... trial and error. Take a picture, chimp, adjust. Repeat until lighting is what you want.

The other way is to use a handheld light meter.


The SB-700 has a "distance priority manual mode" (GN on the mode switch) that lets you configure the distance to the subject and have the flash power set based on that. It's still manual in the sense that you control exactly what results you get, but will assist you with some of the maths involved.

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