(© Ian Plant) White balance is something of a mystery to most beginning photographers, and it can even be a bit confounding for the seasoned pros out there. If you find yourself struggling to understand how white balance works, don't despair—it is actually easier than you think.
White balance is essentially a process by which your camera (or your raw file converter) determines how neutral tones in an image are rendered. More precisely, it is a process by which your camera determines how whites are rendered, but the same process can be applied to grays and blacks as well. A "proper" white balance is a color setting that will render whites as whites, rather than tinted with color. Basically, white balance is a way of removing color casts from an image.
Still a bit confused? Bear with me, this should get more clear. Let's take an example of photographing a white beach ball. If you photograph the ball in bright sunlight during the middle of the day, the ball will look white to the eye. That's because the human eye perceives bright sunlight as being "neutral" in terms of color, so white stays white. Photograph the same ball at sunset, however, and the eye will perceive the ball much differently. That's because sunlight at the end of the day is scattered by atmospheric particles near the horizon, allowing mostly red light to come through. Accordingly, we perceive the white ball as reddish in color
Many other things can create a color cast. If you shoot the same ball on a sunny day in the shade, the ball will look somewhat blueish. That's because the primary source of light will be light bouncing off of the blue sky above. If the same ball is in the shade at sunset, a bright cloud overhead glowing red with the day's last light might bounce a lot of light onto the landscape, turning our white ball red once again.
By one definition, the "right" white balance is one that removes any color cast and renders the ball white. If you apply such a white balance to a sunset scene, however, you are going to lose many of those wonderful red tones. Once we steer away from this objective standard, we end up with a subjective standard, which is of course considerably more murky: the "right" white balance is the one that makes the scene look right. How about that for a tautology?
Never fear, all this means is that white balance is largely a subjective choice that is part of the artistic process. Consider the two images below. Both are the same image taken on a recent trip to Patagonia, processed using different white balance settings. The image was made during a stunning sunrise, when most of the sky lit up red with first light, resulting in a reddish color cast on parts of the landscape.
The first image was processed using the camera's Auto white balance setting. The camera picked a color temperature of 3750 (which is fairly close to the Fluorescent setting) as being the best white balance for the scene. As an aside, personally I find that the Auto setting picks the right white balance most of the time. I made minimal adjustments to this setting when I converted the file in Adobe Camera Raw. To my eye, this white balance looks very close to the way the scene looked when I made the photograph.
Now here's the same image processed using the Daylight white balance setting. I hope you share my reaction—yikes! To my eye, the image appears to be garishly over-warmed, and not at all like it looked to my eyes when making the photograph. All of the tones in the image, including the whites, have a pinkish cast to them. Although the sky has a bit more color than the image above, I simply don't find the colors to be realistic. I'll go with the version above!
As you can see, picking the "right" white balance is largely a matter of taste and experience. Once you understand how it works, however, you will more easily be able to find the setting that is right for you. To learn more about white balance, read my free tutorial Selecting the Best White Balance for Nature Photography.
P.S. I've recently listed my Epic Patagonia Photo Workshop for 2012. It is already filling up fast!