Tuesday, May 11, 2010
Use a simple device to get perfect color in all of your shots
White balance is an adjustment that accounts for the color temperature of the light in a scene. All light sources emit light at a specific color temperature, which is expressed in Kelvin. As the light travels, it may pass through particles in the atmosphere or a filter on the lens, which filters some of the wavelengths. For example, a sunset is usually around 3000-4000K, while bright, midday sun is about 5000-6500K. The sun is always the sun, so the change in color temperature from midday to sunset is due to the amount of atmosphere and particles like smoke or dust through which the light travels. When we adjust the white balance on the camera, we’re essentially telling the camera to account for the color temperature to make the colors more neutral. Whites will look white, greens will look green, reds will look red.
Reflective-Style White Balance
If you have a neutral subject like a white piece of paper or a gray building, you can key off of that. In nature photography, however, we seldom have a white sheet of paper in the scene to use as a neutral point, but you can carry something with you and use that to balance the scene.
The WhiBal White Balance card (www.rawworkflow.com) is a neutral gray card that you can use to set white balance in the field or to make adjustments to a file when you process the RAW files (those of us who shot film and used handheld spot meters will find the WhiBal reminiscent of a traditional gray card and it’s used in roughly the same way). The WhiBal is designed for low reflectivity, it’s perfectly gray, and it doesn’t respond to UV light any differently than the visible spectrum. Place the card in the scene and key off of it, or take a picture with the card in the scene (then remove it for your “real” exposures) and use your processing software to get the proper color temperature setting. You then can apply that color temperature to all your other images shot under the same lighting conditions.
The Datacolor SpyderCube (spyder.datacolor.com) looks like a black-and-white Christmas ornament with a small shiny ball on it. The cube’s surfaces are white, gray and black, and each surface is spectrally neutral. One face of the SpyderCube has a hole that acts as a black trap to give you a control point for shadow detail. You can use it to set the proper color temperature while you’re shooting, or take a picture, remove the SpyderCube and use the image with the cube to set the color temperature for the series when you’re processing the images in the computer.
Incident TTL-Style White Balance
A different way to get your white balance set is with a device that sits on the front of your lens and lets you auto-white balance off of it. Available in most standard diameters, the Brno baLens (www.hpmarketingcorp.com) simply snaps onto your camera lens, and you can attach a neutral or a warm-colored dome to it to get the results you want. The baLens also can do double duty as a lens cap.
ExpoImaging (www.expoimaging.com) makes a few different on-the-lens-type, white-balance tools. Designed for DSLRs, the ExpoDisc snaps onto your lens with a pressure-release friction mount. Press the button and it pops off, leaving you ready to shoot. The company manufactures the discs to strict tolerances, ensuring 18% transmission and neutrality in the visible spectrum. That neutrality, of course, is critical for getting the most accurate white balance possible. There’s also an ExpoImaging white-balance tool for video, as well as one for point-and-shoot cameras.
All of the devices mentioned in this Solutions article can fit into your gear bag and weigh almost nothing. The point is that you should always carry at least one of them in your bag. You’ll be ready with the perfect white-balance tool when the perfect day for shooting comes along.
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