Reader Question: What is white balance and why is it important? Is there a downside to setting my camera to “auto”?

My Answer: Before the rise of digital photography most magazine pictures were shot on color transparency film, more commonly known as slides. Slide film was calibrated to be used in certain lighting conditions because different light sources change the color of the things they illuminate.

We don’t notice the color shifts because our brain’s visual perception tends to correct for radical color shifts. That meant you had to choose to use daylight-balanced film, which was by far the most common, or tungsten-balanced film, which was meant to be used indoors under incandescent lights.

Many photographers didn’t bother to use tungsten film indoors, so their photographs, taken with regular old daylight film, ended up having a pleasing yellow “warmth” that many people took for granted. As a photo editor, this was one of my pet peeves.

Digital cameras were a big improvement in this regard, allowing photographers to adjust for different lighting conditions by changing the white balance settings from one shot to the next. Incandescent lights can make a picture that has been white-balanced for natural daylight look warm or yellowish. Likewise, a photo taken outdoors in the shade will probably look blue because the subject is lit by the huge expanse of sky, not the sun. Having the ability to adjust for these changing conditions helps photography impart a truer reflection of reality.

View Images Taken using the “daylight” white balance preset (Photograph by Dan Westergren)

Digital cameras are usually set by default on auto white balance — which works well most of the time. But this auto setting can fail spectacularly.

Imagine waiting for the last rays of the sun to hit the subject of your photograph, adding just the right twist of color to make the picture exceptional. Click! Then, when reviewing the photo on your screen you see that, though the image is lovely, all the extra color you had waited for is gone. That’s the auto white balance thinking it’s doing you a favor by removing the unnatural color cast! Here’s what I’m talking about:

View Images Taken using the “auto” preset. Notice the blue hue. (Photograph by Dan Westergren)

Auto white balance also can cause problems when making portraits. If the subject is wearing colorful clothing, their skin tone will change from one picture to the next depending on how much of what they are wearing or their surroundings are included in the frame.

To really wrap your head around how white balance works — and why it’s crucial to good photography — I would recommend setting your camera to take JPEGs, then photographing the same scene over and over using the different white balance presets. When you’re through, have a look at the results on your computer so you can start learning to see how your camera sees.

Alternatively, you can shoot with your camera in raw format and adjust the white balance later. But even when I’m shooting in raw I try to manually set the white balance using the presets to match the particular situation I’m in. I spend enough time at the computer without having to adjust the white balance on every picture I take.

Dan Westergren is director of photography for National Geographic Traveler magazine. Follow him on Twitter @dwestergren and on Instagram @danwestergren.

Do you have something you want to ask Dan about travel photography? Join him for a live Twitter chat on January 28 at 12:30pm EST. Follow along and ask your travel photography questions using #enroute.