Jan 31, 2008
Harris Fogel

ExpoDisc and Color Balance Lens
Photo Credit: ExpoDisc / Color Balance Lens
Achieving an accurate white balance has been the bane of photographers working in color since the invention of color photography. In the film age, this meant carefully matching the light source to the film, and even then there was enough squishy room that until the film came back from the lab, you had no way of knowing whether your filter pack was correct or not, or if a reshoot was the only hope. Fast-forward to the digital age, and white balance is simply a click away, or at least so most people think. Set your camera to automatic white balance and usually the results are reasonably good. If you are shooting in RAW mode you have tremendous capability to achieve an accurate white point. Shoot in JPEG, and any color correction after the fact is destructive in nature, like trying to correct a transparency.   

So, what do you do if you want really accurate color balance? The first step is to set your color balance using a calibrated target such as a white board, grey card, or a target like the venerable MacBeth Color Checker, which has been around for years and is now sold by X-Rite. This works pretty well, but the theory is that sensors are sensitive to a wider color gamut than simply visible light as exemplified by infrared cutoff filters employed in most systems, and placement of the target is critical 

ExpoDisc takes one approach to this issue. They make a filter that snaps on to the front of your lens so you can quickly pop it on and off to use. You can take a photo in RAW, or set a custom white balance for use in JPEG mode. Quick and easy to use, we found it very accurate and it is very popular with photographers. We covered this product earlier this year in an interview with Erik Sowder, ExpoDisc’s founder. The key to using the ExpoDisc is to point the camera at the light source you are trying to balance, not unlike using an incident light meter. There are three versions of the ExpoDisc: a neutral version, a warm version, and the ExpoCap, which is integrated into a lens cap. They are all well-made and sturdy, with good attention to fit and finish. It's a great product and many photographers consider it an essential part of their digital toolkit.

Another accurate tool is CBL’s target tool made in Korea. I first saw this at Photokina in Germany, when I noticed a large crowd of people around a booth looking at what at first glance seemed to be just another target. However, the CBL, which stands for Color Balance Lens, is, according to the manufacturers, actually a carefully designed tool that consists of several layers - a grey plastic outer layer with handle, then a mirrored surface with a specially designed calibrated white plastic layer with different types of ridges and patterns. Finally, all this is covered by a clear plastic lens. The idea is that it reflects only the spectrum of light that the sensor should be judging color with. It is simple to use - just point your camera at it, set your custom white balance, and that’s it, although you need to be careful with shadows and how you hold it. The CBL has achieved cult status among critical users, and in our experience that status is deserved, as we found it very accurate in use. The target approach may not fit everyone’s workflow, but if it does, and if you are interested in really accurate color, then take the CBL Color Balance Lens for a spin to see how it performs for you.

Although we didn't experience a problem with color casts, it's conceivable that the color of the clothes you wear might affect your readings, as light reflected from clothing might reflect off the target you hold in your hand. But this could happen with any target in theory. The same issue holds true for the incident light approach, since unless you are close to the subject of the photo, you might not get a truly representative reading of the light sources. This is similar to using a spot meter on the wrong area of an image, or using an incident meter from where you are photographing, instead of from the location of your subject.

Between visits to PDN PhotoPlus Expo in New York and the Photo Marketing Association conference in Las Vegas, I must have seen well over two dozen companies selling some kind of target or filter for white balance. For example, color management leader X-Rite has an entire line of 8 color checker charts including the Digital Color Checker SG designed specifically for digital photography. So, if you want to get really granular, all of these tools will get you very close to a neutral color cast, but none of them will get you 100 percent there, just as even the best color profile doesn't guarantee a perfectly color matched print. There are just too many variables in the chain of command that predicate the idea that any off-the-shelf solution will be the final word. Anyone who has experienced the Zone System knows full well that you can do every single step methodically and by the book, and still end up with negatives that didn't match your expectations. And in the end, scientifically accurate isn't necessarily what you want in your final image. Importantly, if the tool doesn't fit your working style, then all the accuracy in the world won't help you, since you will probably just forget to use it!

Either way, an accurate white balance will help you quickly achieve the color you want, often better than could be achieved in post-production. And the ExpoDisc and CBL are both very competent tools to do just that. Besides, what would you rather be doing - spending your time in Photoshop tweaking colors just to get to neutral, or out shooting more photographs right the first time?

Mac Edition Radio, created by host and executive producer Harris Fogel, web guru Andy Alm and many other leading reviewers, reporters and technology analysts, features in-depth reporting on technology, digital imaging, and photography. Fogel is also an associate professor and coordinator of the photography program at The University of the Arts in Philadelphia. Additional reviews and audio interviews can be found on the Mac Edition Radio Web site.

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