Lighting Tip: Sometimes the Opposite is True

Photographic lighting can be both intuitive and learned. Here’s a case of the latter.

So you’re shooting a portrait with a key and a fill light, and when you take your first test shot the background is way too bright. What should you do? Try moving the key light closer.

Closer? Yes, closer. Light has a unique behavior, and understanding how it behaves can make all the difference. As the distance from the light source increases, the intensity of light falls off very quickly. It’s known as the Inverse-square Law of Light. And once you’re familiar with it, you can use it your advantage.

It works like this; each time you double the distance between the light source and the subject, the intensity doesn’t drop to half, but to a quarter of its original value. So when you move the light closer to your subject it’s intensity increases much more than does the area behind it. When you darken the exposure to accommodate the increased light level, the background darkens more.

This is also the reason why when the subject is very far away, the light intensity doesn’t seem to fall off as rapidly, making outdoor light painting more practical.

When you think about it, it’s not unlike using a zoom lens. When you stand in one location and work the zoom to crop your shot, your options are limited and you might not always gets the best perspective. But if you set your zoom for the perspective you want, and “zoom” in and out with your feet you can have both the crop and angle of view you need.

It’s the same way with lighting. Sometimes, just changing the exposure or the light intensity is not enough. You also need to consider changing the location of the lights in order to get the right balance of key, fill and spill light.

I love working with speedlights over monolights for just that reason. They’re lighter and thus much easier to move, so they don’t discourage you from making the physical adjustments to your lighting setup that you need to.

So next time you’re working with strobes, or speedlights (or even reflectors) keep in mind that if it doesn’t make sense, it might be just what the doctor ordered.