Monday, September 29, 2008
Pro Tips: Chromozones
Gel your lights to create any colored background
The assignment was called “Chromozones,” and it went like this: Using strobes in the studio, add gels, bracket several exposures and end up with a template for reproducing almost any color on the background. The best thing about the resulting chart was that the strips of unmounted transparencies could be used to match colors directly with subjects in the scene—say, a bright red sweater or a product’s cool blue packaging. Most amazingly, though, was that it taught you how to turn a plain gray wall into a vibrant background.
For starters, choose a wall and a color. A gray or white wall (or seamless roll of paper) makes for a nice neutral foundation. You’ll be astounded at the rich color you can get from it. When choosing a color to emulate, try to pick one that you think you might like to use on a regular basis. That way, you’ll end up with practical knowledge when the assignment is completed.
Set up two strobes with umbrellas to create an even illumination across the background; meter it to make sure. (A reflective meter may be a bit more accurate than an incident meter, but you probably can make both work fine.) The setup also could be made with one light or even a light without an umbrella—but the inclusion of a second soft source makes it that much easier to ensure that the light and color will be consistent across the frame.
Gel the strobes, using the same types of gels on each light. Use a manual white balance, neutral to the ungelled color of your strobes, like a daylight preset. To make the test really worthwhile, you’ll have to cover a four-stop exposure swing in each direction, so set your lens to four stops from wide open. On an ƒ/2 lens, for example, that would be ƒ/8. Adjust the power and distance on the gelled strobes to get an even ƒ/8 illumination across the background. Then it’s time to start shooting.
To make a series from light to dark, open the lens all the way. This ƒ/2 exposure will be +4, or four stops overexposed—pretty bright white even with the gel. Then stop down for each exposure, to ƒ/2.8, ƒ/4 and so on, one stop at a time, all the way through to the end. When you download the pictures, you’ll be amazed by what you have—a range of shades from pastel down through deep, dark, almost black tones. If one of them isn’t a perfect match for your subject, chances are good that a compromise between two of them will be.
Armed with this information, you can create almost any color under the sun, right inside your studio.
The only potential pitfall in this test comes from the lens you use. Let’s say it’s not an ƒ/2 lens, but an ƒ/2.8 instead. If the minimum aperture is ƒ/22, that’s only a six-stop range. So when you get down to ƒ/22, you’ll have to adjust the flash power to reduce it a full stop, simulating an ƒ/32 exposure. Reduce the output another full stop to simulate ƒ/45 and complete the test.
Since I did the original assignment on film, an added benefit was the physical color swatches it produced. Shooting on transparency film and bracketing an eight-stop range provided an uncut strip of film from, say, light pink to deep red. They won’t come in that handy strip, but you can still re-create those swatches with a digital camera; just print a contact sheet labeled with exposure information as a handy reference.
To be able to match multiple colors at a moment’s notice, repeat the test for as many gel configurations as you’d like. When it comes time to shoot a subject in this scene, remember that the farther the subject is from this background, the easier it will be to light separately. Don’t hesitate to flag the main light to keep it from contaminating the background, and make sure you meter your key light to match the preestablished background exposure.
Armed with this information, you can create almost any color under the sun, right inside your studio. Instead of relying on a fix-it-in-post attitude, you’ll take pride in your ability to do it the old-fashioned way—with your expert knowledge of studio lighting. Best of all, you’re bound to impress your clients when you match colors perfectly right before their eyes.