The Inverse Square Law can sound really confusing but has practical  implications for all kinds of photography. David Bergman from AdoramaTV explains its best practices in hands-on examples further below.

“The inverse square law tells you how quickly light falls off the further away it is from whatever you’re shooting.  You might think that as you double the distance  between your subject and the light source that you would have half the light hitting them, but the truth is you actually get a quarter of the light. And if you double the distance again you get 1/16th of the light.  So it really has to do with the way  that the photons of light  spread out as they travel. They don’t all hit your subject equally.” 

“You can geek out over the science all you want but I’d rather talk about it in  practical terms.  Here’s the only thing you really  need to know – the light falls off a lot faster if the light source is closer to your subject. This is really useful to know so you can control the ratio of light on your subject and the background.  In the following example I will be shooting with my friend Tango. He’s standing in front of a white  background. I’m only using one light and it’s pretty far away from him.”

“You can see that the background is relatively bright but now let’s move that light in.  So it’s a lot closer to Tango, of course it’s a lot brighter on him now. So we  have to change our camera settings so that he’s properly exposed.”

“But now look at the background, it’s a lot darker.  So without moving my subject at all I can  create a completely different look from my photo. This is also important to know when shooting a group shot of people like a band, for example.  If everyone’s standing different distances from the light but you want them to be lit pretty evenly then you have to get your light further away from the entire group. Don’t stress out about the science behind the inverse square law,  unless you’re into that kind of thing. Photography is really about  using and controlling light. So use those scientific principles  to make your pictures look exactly like you want them to.”

*For more information visit AdoramaTV YT page, and of course you can keep up with David on Instagram and Twitter @DavidBergman. LATEST UPDATE: David opened up new IGTV episodes where you can ask him questions live! find out more at http://www.AskDavidBergman.com

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Watch the full episode with David Bergman and Adorama TV: