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Canon EOS 40D Guide to Digital Photography by David D. Busch

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Red-Eye Reduction

Your EOS 40D has a fairly effective Red-Eye Reduction flash mode. Unfortunately, your camera is unable, on its own, to eliminate the red-eye effects that occur when an electronic flash (or, rarely, illumination from other sources) bounces off the retinas of the eye and into the camera lens. Animals seem to suffer from yellow or green glowing pupils, instead; the effect is equally undesirable. The effect is worst under low-light conditions (exactly when you might be using a flash) as the pupils expand to allow more light to reach the retinas. The best you can hope for is to reduce or minimize the red-eye effect.

The best way to truly eliminate red-eye is to raise the flash up off the camera so its illumination approaches the ...

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