What’s the first thing that a photographer learns? Photography is primarily about light. Composition and subject selection are important too, but nearly every decision in photography comes down to manipulating light.

Bad light, bad photo. There’s no escaping this truth, which is why you owe it to yourself to learn about one of light’s most fundamental properties: the Inverse Square Law, which sounds scarier than it actually is.

The law in a nutshell: as light travels, it gets exponentially weaker with distance. Common sense says that if the distance from light source to subject doubles, then the brightness should decrease to one-half — but this isn’t the case. The brightness actually decreases to one-quarter.

Simply put, the closer an object is to a light source, the more of a light gradient there will be. Conversely, the farther an object is from a light source, the flatter the light fall-off will be. Want dramatic shadows? Get closer. Want a smoother look? Get farther.

Here’s another tutorial that’ll help cement the concept:

This principle is especially important when you’re taking photos with a speedlight, which is common when taking portraits and shooting pictures of food.

Have you used the Inverse Square Law to improve your photos before? What other lighting tips can you share with us? Drop a comment down below!

Image Credit: Freckled Woman Portrait by Irina Bg via Shutterstock

1. Chris
November 12, 2015 at 8:38 pm

"as light travels, it gets exponentially weaker with distance"

No, not exponentially, but as the name "inverse square law" says, squreadly, i.e. polynomially.

• Joel Lee
November 18, 2015 at 2:57 am

Thanks Chris. I meant in the colloquial sense (which is admittedly wrong in the mathematical sense). Basically, "non-linearly". Hope you can forgive that! You're absolutely right, though.

2. Anonymous
November 11, 2015 at 3:10 pm

"The brightness actually decreases by one-quarter."
Shouldn't that be "TO ONE-QUARTER"?

• Joel Lee
November 11, 2015 at 4:37 pm

Whoops, you are right. I've updated the article. Thanks for catching that!