Adding WB to the exposure triangle… err… square?
by eNoBlog on Nov.06, 2009, under Post-processing, Techniques
If you take control over other aspects of our photography, should you let the camera automatically select White Balance (WB) for you? Most if not all cameras come with an Auto-WB mode, and initially, as you learn to use the camera, it is perfectly okay to let it do its thing. However, as you perfect your camera skills and start taking control over the exposure triangle, you need to consider whether you want to leave WB to chance.
Yes, I said chance, because unfortunately, depending on your camera’s inner-smarts, from one situation to the next, the colors you end up getting due to the automatically selected WB setting may be a bit of an adventure. I suggest that you add a fourth corner to make an exposure square: WB, aperture, shutter speed and ISO. This will mean, however, that you will have to determine and set the “correct” WB. How do you decide this?
Methods for determining WB abound, but before we discuss them here and in future articles, let’s first examine a foundational choice for selecting the “correct” WB:
- Do you want the colors to accurately reflect the scene as you photographed it, sometimes called achieving “actuality,” or
- Do you want the colors to feel right, as in, for example, making sure that white is true white and not a color-cast version of white?
Just as with determining the correct exposure one first should decide how you intend the photograph to look, its purpose, so too you will need to decide whether you want actuality, namely an exact, accurate representation of the scene’s colors, or whether you want a different effect, as when you would want early morning sunlight to be a tad warmer because that fits the mood you want for your final image.
To keep things simple initially, let’s say you shoot for actuality. Most cameras have built-in WB settings such as Direct sunlight, Cloudy, Shade and Flash that you can switch to depending on the lighting situation at hand. Other settings usually include Fluorescent and Incandescent, which at least of my Nikons, I have found to be less than dependable, though I often choose them anyway to get me in the ballpark. For these and other more challenging lighting situations, such as when two or more disparate light sources are involved, other methods may be required.
The brute force method many use rather successfully involves shooting RAW, then adjusting WB in post-processing. This has both advantages and disadvantages. On the plus side, you can shoot now and ask questions later. On the minus side, you have to answer questions later, often without the benefit of being in front of the scene you shot to compare your WB adjustments against the actual scene. This is often acceptable, however. I have found through experience that color actuality isn’t as big a priority as some would make it. In the end, it’s about whether the photograph works as a whole, and color, regardless of how we may feel about it initially, is not always the overriding factor. Even if the image is about color, having less than accurate color isn’t necessarily a problem. Besides, probably half of us are color blind in lesser and greater ways and wouldn’t be able to agree on what the right color is anyway (think on that for a while).
When you don’t want to guess at color in post-processing, by far the most reliable way to set WB is with a pre-set shot against a gray (or white) card. Expo-discs and other like approaches essentially fall into the same category. Accuracy is a benefit of this approach, but it isn’t always practical, as when you are changing lighting conditions often during a shoot (now you’re shooting shady areas, now you’re shooting sunny fields), or when your subject is lit under light miles away, and that light source is not available where you are standing.
If your camera has Liveview and features the ability to change WB temperature, turn on Liveview and crank the WB until the colors you see in the LCD match the scene before you. This is quick and fairly trivial to do, but it also depends on the LCD’s color accuracy, which in the end makes it an approximation – though in my experience it is a very good one.
Hopefully this information will help you figure out how to set WB. Now you have to go back to those two options mentioned a few paragraphs ago and decide what WB you want to accomplish your goal for a given photograph. Stay tuned for future blog entries for additional suggestions and illustrations how one might approach WB selection to meet each photograph’s needs.
