Illumination Strategy Main Light

Illumination Strategy

Main Light. A multiple flash setup for hummingbirds begs for a uniform illumination pattern over a fairly large area. My flashes are typically ~18 inches from the bird. With all the flashes working together, I try strive to uniformly illuminate an area 12 inches wide by 8 inches high, at the focal plane. This is area is approximately the field of view of a 400mm lens at 15 feet.

I mapped out the illumination patterns of individual flashes at various zooms (the hot shoes flashes typically zoom from 24mm to 105mm), and found that they accurately zoom with the stated focal length. And furthermore, the illumination across the rectangular frame projected by the flash’s optics is remarkably uniform.

By zooming to 50 mm I find that I can cover a 12 in x 8 in area uniformly for a flash 0.5m distant. I zoom all flashes to 50mm and try to aim all flashes at the center of the 12x8 field. The light from all the flashes is additive. With the multiple flashes aimed at the same point, they illuminate the subject as a large source. Remember, all flashes are the same model, all set to manual, all set to the same energy. Control light levels from the flash by aiming or zooming, or changing distance, not by changing energy.

However, shading is also key to a good portrait. Flashes on one side can be zoomed or redirected relative to the other in order to create “main” and “fill” lights for portraiture. This assumes, of course that you have some control over the position of the bird.

Figure - Shading is key to a good portrait. The ceiling of the Sistine Chapel is actually smooth – he painted it in relief!

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