Capturing accurate color when you click the shutter makes your overall digital photography workflow easier. Good color and exposure out of the gate means that you spend less time adjusting sliders and more time making prints, web galleries, and slideshows.
On a recent assignment in Iceland, I used a simple device called an ExpoDisc to set white balance on my Canon DSLRs. Efficient workflow was critical on this trip because we often shot until 11 p.m. during Iceland's long summer days, then we'd have to return to our work area to process the images before retiring for a few hours' sleep. The faster I processed, the more sleep I would get.
In short, the ExpoDisc saved me hours of post-production work. I rarely had to make a color correction, and was therefore able to put my energies toward making great prints with the Epson R2400s available in the workroom. In this article, I'll show you how to use the ExpoDisc and provide a few examples of the difference it makes.
The standard model looks like a thick filter that snaps onto the front of your lens. The inside layer is translucent white and the outside is honeycombed glass. The ExpoDisc is tethered on a handsome blue lanyard that slips over your neck, keeping it handy while you're working. It has a removable clip that allows you to detach the disc, put it over the lens for reading, then reattach it to the lanyard when you're finished. The ExpoDisc comes in many diameters; I recommend that you get the size that fits your largest diameter lens. You can use it on all of your other lenses, too, by simply holding it in front of the objective lens.
The ExpoDisc snaps over the front of your lens, enabling you to easily create a custom white balance setting.
It's designed for cameras and camcorders that have a custom white balance setting. These days, that's just about any serious amateur or pro model. In the past, I hadn't used custom white balance as much as I should because it was cumbersome. The ExpoDisc changes all of that. In less than a minute, you can create a custom white balance setting that allows you to tailor your color capture to the temperature of the dominant light source.
If this sounds sophisticated, it is. But the process is also very, very easy. I'm going to walk you through the steps for a Canon Digital Rebel XT. I've used the ExpoDisc successfully on other Canon models, including my 5D. We also calibrated a Nikon D200 without breaking a sweat. So even if you don't use Canon, you'll get the gist by following along with these steps.
In this section, I'll show you how to set a custom white balance setting with the ExpoDisc on a Rebel XT. Once set, you can use it exclusively for lighting your photographing, or switch between it and other WB settings on your camera.
This existing light portrait was captured with the couple facing an open window on a cloudy day. Generally speaking, the tendency is to use the Cloudy white balance setting to offset the strong blue tones associated with this type of lighting, as illustrated in the top photo. Notice the difference when using the ExpoDisc to color correct (bottom photo). The whites are much cleaner, and skin tones are more natural.
Put your camera in shooting mode and go to the white balance menu. Select Custom White Balance. "Custom" is usually the last option on the list. Press the "Set" button to lock it in.
Put your camera in manual focus mode (just for the test shot), and put the ExpoDisc over the front lens. Point the camera at the dominant light source and take a picture. So, if you're in a room where the dominant source is an open window, point the camera at the window. If the dominant light source is overhead lighting, then point the camera in that direction. Once you take the picture, it will record a gray image that you can review on your LCD.
Take off the ExpoDisc, return your camera to autofocus mode, and go back to Menu options (by pressing the Menu button.) Scroll down the list until you find "Custom WB." This is where you'll tell the camera to use the image you just recorded as your custom color guide.
Once you open "Custom WB" in the menu, the camera will ask you to choose an image. The gray picture you just captured will be displayed on the LCD, since it is the last image you recorded. Press the "Set" button, and you've now calibrated your camera for the specific lighting you're photographing. Take pictures at will until you change lighting situations. I recommend that you return the camera to the Auto White Balance setting after you finish the shoot.
When you review your images, you'll see a difference right away in the quality of the photographs. More often than not, the white balance will be improved. But I'll cover some caveats and advanced techniques in the following section.
When you're in a mixed-lighting situation, be sure to key off the strongest light source. You can determine which source is the strongest by using your camera's light meter, although it's usually pretty easy to determine just by looking.
This outdoor portrait was captured in open sun with a reflector to one side. Most photographers would be comfortable using the Daylight white balance setting, as illustrated in the top picture. But the ExpoDisc improves the color balance (lower image), even in an easy lighting situation.
For the most flexibility, shoot in Raw mode. The custom white balance setting via the ExpoDisc becomes your "As Shot" white balance setting when processing your pictures in Adobe Camera Raw, Lightroom, or Apple's Aperture. If you want to see how other settings look, you can select Auto, Daylight, Cloudy, or any of the others. More often than not, the As Shot setting will have the best color balance. But if it doesn't, you can change to one of the other settings without any image compromise (this is the beauty of Raw).
You'll notice that the ExpoDisc changes both the Temperature and Tint settings as you switch among the white balance settings in your image-editing application. This gives you a good idea of how mild or strong the ExpoDisc setting differences are compared to the other white balance presets.
Accurate color capture saves post-production time. This is true for Jpeg and Raw shooters alike. I think the ExpoDisc is particularly handy for those recording in Raw, because it essentially gives us an additional white balance setting to choose from. Often, it will be the best option. But for those times it isn't, Raw shooters still have the other normal presets available without penalty.
I now carry the ExpoDisc with me at all times. Along with a polarizer filter, it's my essential image-adjustment accessory.
Derrick Story is the author of The Photoshop CS4 Companion for Photographers, The Digital Photography Companion, and Digital Photography Hacks, and coauthor of iPhoto: The Missing Manual, with David Pogue. You can follow him on Twitter or visit www.thedigitalstory.com.
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