Auto White Balance versus Pre-set White Balance
With the exception of a few SpongeBob and Hello Kitty point-and-shoot digicams, every digital camera allows you the option of setting the White Balance (WB) to a selection of specific pre-sets (Daylight, Cloudy, Fluorescent, Tungsten, etc.) or Auto, and for the most part, you’ll get acceptable results regardless of whether you set your camera to Auto or man-up and choose one of the camera’s pre-set modes. But what about getting the best results?
Those who shoot RAW files can rightfully argue it’s a moot point, and in most cases, even JPEGs are well within the parameters of post-capture tweaking in Photoshop or similar photo-editing applications. All that said, why sweat the details? Maybe the best comeback for this question is that with little additional work on your part, you can easily obtain higher levels of white balance accuracy.
While the essence of this topic can be applied universally to all digital cameras, it’s important to note that while the WB systems of almost all cameras operate on the same principles, the results they produce and the degree of white balance accuracy varies from camera to camera. In order to understand how accurate (or inaccurate) the WB settings are in your particular camera, it’s worth taking the time to photograph different scenes using your camera’s Auto mode as well as its pre-set WB modes to see how you camera interprets white balance levels under different lighting conditions.
Let’s start by picking apart your camera’s Auto WB (AWB) mode and discuss how it “thinks” and what it does. The basic job of Auto WB is to maintain correct levels of color balance―with no distracting color casts―regardless of the ambient light source in which you’re shooting. As for accuracy, AWB is pretty good if you’re shooting under bright sunny (or near-sunny) skies 2-3 hours after sunrise and 2-3 hours before sunset. This is the time of day when the color temperature of the ambient daylight is 5000° to 5500° Kelvin, aka, “Daylight.”
Sunrise, sunset and the first hour or two following and preceding these portions of the day are, color temperature-wise, far warmer than mid-day light,* and the warm quality that makes sunset and sunrise photographs so special can be easily compromised if you’re shooting in AWB mode. This is because the AWB mode is specifically designed to analyze the color of the light and readjust it to a “correct” rendition of daylight.**
In Auto mode (left), the warm glow of late afternoon light is suppressed compared to the warmer, more saturated tonality of the same scene captured in Daylight mode (right).
There are two easy ways to avoid this problem. The first is to set the WB of your camera to Daylight. By doing so, you are locking the color parameters of the scene you are photographing to about 5500°, which ensures pictures taken during the waning and waxing hours of daylight will retain their warm glow. Your second choice is to set your camera’s WB to Sunrise/Sunset or similarly-named WB mode, which in addition to maintaining the color ambience you’re trying to capture, also corrects for underexposure factors common to early morning/late afternoon picture-taking . When in doubt, or if the scene is so good you’ll kick yourself if you blow the opportunity to capture a killer pic, you should shoot in both Auto and Daylight modes and ultimately choose between the two.
These same considerations should be taken into account when shooting under tungsten lighting, fluorescents and other lighting sources, though due to the multitude of standards and types of artificial lighting you’re likely to encounter along the way, artificial lighting can be trickier than daylight. Interiors can be especially tricky to shoot when you take into account that many contemporary lighting fixtures contain compact fluorescent bulbs, whose color temperature can be deceiving to the eye. And when dealing with mixed lighting, especially lighting fixtures from more than one manufacturer and of varying age, all bets are off.
In Auto mode (left), the lobby of this building takes on a gold cast, unlike the Fluorescent mode (right), which renders the color far more accurately.
As mentioned above, your camera’s AWB mode will usually do a fine job of rendering the color of scenes that don’t challenge the “norm.” The problems start when you go beyond normal parameters, i.e., sunrise/sunset, and mixed and/or hybrid light sources. Regardless, if you take the time to shoot test images under various lighting conditions and learn the way your camera “thinks” under different lighting conditions, you can vastly improve upon the results of your efforts wherever and whenever you’re shooting.
On a parting note, when shooting under questionable lighting conditions, always try to shoot the scene in a choice of WB settings. If your camera has a WB Bracketing mode, take advantage of it. And always keep in mind RAW files, which contain all of the image data your camera recorded when you pressed the shutter, which offers you the option of nailing the accuracy of both your exposure and WB long after the moment of image capture.
* The ambient color of winter light (mid-October to mid-March in the northern hemisphere), like the light at sunrise and sunset, is similarly warmer than the ambient color temperature of spring and fall daylight because the sun remains closer to the horizon. Likewise, summer light is noticeably bluer (or “colder”) because the sun peaks higher in the sky than it does in spring, fall and winter.
**The same so-called corrections are also commonly made to photographs of sunrises and sunsets produced by kiosks and commercial labs. Rather than replicating the warm look that inspired you to take the picture in the first place, they often “cool them off,” rendering them cold and lifeless.