Pure white backgrounds are essential to most portrait, food, and product photography. You’d think setting up a pure white background is as easy as setting up a white screen or cloth behind the subject. That’s until you review your shots. Your white background all of sudden doesn’t look that white at all. Gavin Hoey has a trick for making your background looks pure white every time you need it:
Why Does My White Background Look Gray?
There’s something that you need to know about white backgrounds and why they don’t always appear perfectly white when photographed. It’s all about the inverse square law. The inverse square law is a law of physics that governs many things, including light and how it behaves when traveling over a distance. You can learn more about it here.
Now that we know about the inverse square law, it’s time to take care of it.
Step one is to push the key light away from the subject, and in doing so away from the background, as well. According to the inverse square law, light fall off is more dramatic over the initial distance. It’s not as dramatic as the distance increases. So when Hoey takes another test shot it results in this.
As you can see, the background is a touch whiter than before. Do keep in mind that in between the two shots Hoey increased the power of the key light to compensate for the increase in light to subject distance.
Step two is to bring in an additional light. In this case, Hoey used a light placed just behind the model and away from the line of view of the camera to illuminate the background.
OK, the light is placed. But at what power should you fire it? Consider the following:
- The power of the background light should be at least the same as the key light.
- If the background isn’t too clean, fire the background light at least a stop over the key light’s power.
- Take a reading off the back of the subject’s head (if you’re taking a portrait). It’s pertinent to know how much light is being reflected off the background and on to the back of the subject’s head.
- Take test shots and continue to adjust the lights until you get just the look you’re after.
A word of advice here. Hoey uses a hand-held light meter to test the power of the lights and then adjust their output. A hand-held light meter helps to measure the incident light and better manage them in a studio environment. You may consider investing in one.
OK, the lights are set and here’s how they stack up:
Hoey takes another shot. The background in this one is perfectly white as you can see here.
But the fun doesn’t end here.
Watch the rest of the video for some cool editing tips and maybe ideas for you to replicate.
Like This Article?
Don't Miss The Next One!
Join over 100,000 photographers of all experience levels who receive our free photography tips and articles to stay current: