The Willems Rule for Indoors Flash

So.. for indoors flash in a ‘normal’ environment (i.e. a room with not too much, not too little light), here is my new, “restated-as-an-easier-mnemonic” rule of thumb:

The 400-40-4 rule (a.k.a. the “4-4-4-rule”).

As a simple starting point, do the following:

  • Flash aimed 45 degrees up, behind you
  • 400 ISO
  • 1/40th second
  • f/4

That will give you an ambient light exposure of around -2 stops. Which looks like this:

Of course if your background is now too dark, you can raise ISO, lower f-number, or slow down shutter. If on the other hand the background is too bright, lower the ISO, select a faster shutter speed, or increase the f-number.

Often, simple rules of thumb are the secret to success. And simplicity is key – “4-4-4” sounds simple enough to remember, no?


7 thoughts on “The Willems Rule for Indoors Flash

  1. Michael – what are your thoughts on using a non-VR (or IS) lens and having the shutter speed lower than the focal length? ie (shutter set at 1/40th second with a focal length of 70mm on a crop camera). Will the sharpness suffer because of the shutter speed setting due to the slight motion blur…provided that I dont have the steadiest hands? just a thought…

  2. Pingback: Slow flash – a misnomer |

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