PhotoVision’s One Shot Digital Calibration Targets; White Balance And Exposure, Right In The Camera

Remember the old Kodak 18 percent Gray Card that we used as a neutral target to determine exposure, without undue influence from bright and dark tones? I still have a bunch of those lying around. There were several problems with the card; holding it the wrong way might cause a glaring hot spot. Second, it was cardboard, not built to last. Third, it didn't travel well--at least not in a handy size (and swatch pads are too small to be practical, the way I see it).

Now, fast forward to the digital age. Digital camera manufacturers originally recommended using a white surface when making Custom WB (White Balance) settings (some mistakenly still do). Over time, we began seeing the wisdom of returning to the ubiquitous gray card to customize white balance because we still needed the target to be correctly exposed: a neutral gray card delivers that exposure; a white surface bounces back too much light, often producing an underexposed reference image. Yet, a return to the gray card brings us back to its shortcomings. What we need is something more durable and more utilitarian. That something turns out to be one of the handiest, low-tech tools I've ever come across: the PhotoVision One Shot Digital Calibration Target. It was designed by photographer/lecturer Ed Pierce and is manufactured by Westcott, a company with a renowned reputation for lighting accessories.

Sisters

I used on-camera bounce flash to photograph these two sisters, with a kicker panel to add a little fill and catchlights to the eyes. Working with my Canon EOS 5D and 580EX flash, I set both to Manual mode, then took an incident meter reading. I next made an exposure with the One Shot Digital Calibration Target, asking one of the girls to hold it in place. Note that the white panel is facing upward, to better read the bounce lighting. I was now able to set Custom WB and the camera exposure, letting the girls playfully interact during this series.
All Photos © 2007, Jack Neubart. All Rights Reserved

Why We Need A Calibration Target
I used to think, shoot raw with your D-SLR, set white balance to Auto WB, and take care of color balance during raw conversion or in Photoshop. And things were going along nicely until it dawned on me: what exactly was that color I was seeing back then? I lacked a reference point, so I trusted to memory. Memory, as cognitive theory teaches us, can play tricks.

Every color has shades, and while it may not be necessary to pinpoint a shade exactly in every situation there are clearly times when we want--no, when we need--to get the color right at the moment of exposure, as in a portrait or when shooting a commercial product on a tabletop set. Companies go to great lengths to create a corporate or product identity that extends from the design of a logo to the colors expressed in that logo. We know the Target logo from its bright red target, but if that red were a rust red or maroon, it would just be an image of an ordinary target, not a company logo. Same with faces--especially people half a world away that we may never see again. We may not pay this close attention to color on our TV sets, but we had better do so in our digital images. Granted, having your computer monitor calibrated correctly is a great help when it comes to evaluating the color balance. But before you even get to this point, wouldn't it be nice to know that you had the color right from the get-go?

Tree Bark
Custom White Balance
Auto White Balance

Was I barking up the wrong tree with this picture? Experience dictated against relying on Cloudy or Shade WB in shaded conditions, either often producing overly warm results. So I brought the One Shot Digital Calibration Target into the picture, again hand holding it. And curious to see what Auto WB would give me, I made a second exposure. Clearly, Custom WB delivered the better picture. I didn't have to later look at the picture and ask, was this the correct color? I knew it was.

Beyond that, there is the matter of exposure. I'll admit, I use my Canon EOS 5D's evaluative metering system extensively. And even when I bypass it and go to incident metering with my Sekonic L-558 meter (or any other flash meter) for ambient-light or flash readings, I still have only one thing: a base exposure reading. Even when I use the camera's live histogram to examine exposure levels, black and white points have no reference anchors to which I can key important shadow and highlight values to ensure they don't get blocked up or blown out.

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