Light Source: Using Diffusion (page 2)

The farther from the light source, the greater the diffusion. You can hang diffusers on the light itself, on its barndoors or on a Century stand between the light and the subject. For a really diffuse effect, you can bounce the light off a reflector.

Spotlights (and some scoops and broads) have filter holders that accept a metal sandwich frame holding spun glass or gel cut to size. This setup is good for lights too high or otherwise too difficult to reach easily. Scoops are generally safe, but broads and spots should be checked periodically to make sure the media isn't charring. Focusing spot lamps in the "flood" position can reduce the heat a little.

Spots and broads have side barn doors that are ideal for holding spun glass, but plastic doesn't work quite so well. Spread the diffusion across the already-positioned barn doors and clip it on with wooden clothes pins. The extra distance from the lamp makes the diffusion more effective, and the media will stay safely cool indefinitely.

For a really soft effect, try clamping spun glass or plastic with a C-stand placed several feet in front of the spotlight. Of course, if you go too far out, the cone of the light beam will be wider than the diffusion, but sometimes that's just what you want. For example, you can soften the light on just the face with a circle of spun glass stapled to a thin wire frame.

The larger a light source, the more diffuse it is. Bouncing a spotlight beam off a 4x4-foot white foamcore reflector creates a very soft illumination. A bed sheet is even bigger and softer, but the dramatic light falloff means that this solution isn't very flexible.

For product shots and special portraits, there's nothing like a cloth tent. Simply string a clothes line and hang a sheet to create a side and a roof. Lighting through the sheet creates an essentially shadowless design.

Small tents work well in a studio, but large ones do better outside where the sun is your light source. (Of course clouds make fabulous diffusers, but they are notoriously hard to control.) Bed sheets and black gardening shade cloth are good options. Orient the clothes line and sheet so that the sun filters through both the top and the side. The results will amaze you.

Also, in bright, filtered sunlight, the camcorder's aperture will be small enough to deliver good depth of field, which is essential for shooting very small objects especially.

Incidentally, outdoor tents are also useful for copying photos onto videotape. Even glossy prints behave themselves in the tent's shadowless environment.

You can light human subjects through sheets hemmed and mounted on PVC pipe frames. An assistant can hold a framed diffusion sheet between sun and subject, even for setups as wide as a medium shot.

You can often omit diffusion in wider shots, where higher contrast is not as big a problem. Unlike flexible reflectors, diffusion screens work fine on somewhat windy days because the light travels through them, rather than bounces off them. Do make your assistant aware, however, that a 4x4-foot diffusion screen is a very efficient sail in a brisk wind.

Diffusion does have limitations in bright sunlight since it changes the character of the light. This doesn't matter if you're shooting only close shots, but your close shots won't match your long shots. When I need both kinds of setups, I prefer screening, which reduces light intensity without changing its quality too much.

Good shooting!

Contributing Editor Jim Stinson is the author of the book Video Communication and Production.

Before we look at diffusion setups, we need to emphasize safety precautions that really ought to be obvious. Excepting fluorescents, all lights grow hot enough to char filter media, burn fingers and start fires. Before deploying any diffusion material, you need to understand:

• How hot the light gets
• How fire-resistant the medium is
• How long the diffusion must remain on the hot light

Even knowing these things, a conscientious gaffer will re-check the diffusion every few minutes to make sure it's not overheating. Unless the light is inaccessible, I prefer to avoid using diffusion in circular light filters. Even spun glass and the best heat-resistant gels will eventually brown and char like forgotten pot roasts.

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