PhotoVision’s One Shot Digital Calibration Targets; White Balance And Exposure, Right In The Camera Page 2

Think of photographic exposure and white balance as a sailboat drifting on the open sea: without guidance, the boat moves in the direction the wind blows it. It is up to you to steer the rudder and direct the boat's course. The calibration target is like a compass or sextant, helping to steer you in the right direction. As with a compass or sextant, the calibration target must be used judiciously for it to work properly, but in practice it couldn't be easier.

The PhotoVision One Shot Digital Calibration Target simplifies the entire process by providing highlight, shadow, and mid-tone targets all in one. The mid tone, or 18 percent gray target is also the one you use to key in Custom WB. See the sidebar on working with the One Shot Digital Calibration Target.

Of course, when light levels change dramatically or the light takes on a color cast, you may have to shoot a new reference image of the calibration target. In more controlled environments involving studio lighting and subjects who are constantly moving about, such as a professional model who changes position every few seconds, a chef preparing a meal, or young siblings having fun together, you can simply adjust the lens aperture on the fly or just leave corrections for later, when working with the images on your computer.

Red Building With Sky

Because the grass was actually artificial turf, it was difficult to pinpoint the green hue. So I photographed the building behind the soccer field with some blue sky above, using the sky as an easily identifiable color and proof that the calibration target's Custom WB setting provided the optimum color balance.

A Dual-Purpose, Collapsible, Reusable Resource
These squarish targets come in various sizes, and all but the smallest are collapsible--which means they are all highly portable and unquestionably practical. Since I received my first set of calibration targets, they've undergone some improvements. The fabrics are now stain-resistant and can be cleaned with mild soap and water. More important still, the new fabrics have undergone tighter quality control for consistency; targeting crosshairs were added to make it easier to focus, especially with autofocusing.

What's more, the mini target, perhaps the most convenient calibration target ever, now comes with a lanyard, so you can wear it around your neck, which means you can continue to shoot without worrying about putting it down somewhere and forgetting it or getting it dirty. And it no longer uses a metal frame. Instead, it now sports a more pliant, yet fairly rigid, foam frame so it will mold itself to tight spaces in a camera bag (it's fairly resilient and pops back into shape with ordinary use). That also means you can leave it in a pocket as you walk through airport security checkpoints without worrying over setting off alarms.

The medium-sized (14" and 24") targets will fit in the laptop compartment of a camera bag, provided you're not carrying a laptop (or it may help to fill an overly spacious compartment), and all weigh next to nothing. I've found the 14" and mini targets to be the most useful. The largest size (32") would be suitable for group portraits.

Custom White Balance With Studio Lighting

For these exposures, I used my Interfit flat-panel strobes. After making an incident meter reading, I asked this lovely model, who is both actress and chef, to hold the target for a test image, from which I set Custom WB. This established my basic exposure settings, from which I veered a bit in response to changes on set. I used the same lighting on a different occasion to photograph confections she'd prepared, keying color balance to that earlier test exposure of the target.

When you pop a collapsible target open for the first time you'll be amazed at what reveals itself. Flip it over and you find a fully functioning bounce reflector, even on the mini. The surface color varies with the size of the calibration target, with white on the 24" target and silver on the 14" and mini. The color reflected off the silver target appears to be fairly neutral (some silver reflectors throw off a bluish light) and not overly specular. The largest target comes with a reversible silver/gold reflector (gold for warm-toned fill) over a neutral, softer white. The largest reflector is great for portraiture in the studio or on location. The smaller reflectors can be used with tabletop sets or outdoors, with flowers, for example.

Prices range from $37.50 for the mini One Shot Digital Calibration Target to $129 for the 34" target, but you can buy the Utility Kit, which comes with the 34" and 14" targets, plus two minis, for $239--essentially, you're getting that second mini free. Or buy two minis, one for your vest, the other to be stored in the camera bag, so one is always at hand.

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