Most ring flash units are physically attached to the camera with a bracket
that ensures the lens is strategically centered in the flash unit’s hollow ring.
While the quality of light the ring flash produces can easily be utilized like a
dead-on beauty light, it can also cause red-eye. This red-eye appears because
the lens and flash unit are at the same angle to the subject’s eyes, so the light
from the flash reflects off the blood vessels in the rear portion of the eye.
Though red-eye can be easily fixed in Photoshop, it’s easier to reduce or
eliminate it by simply increasing the ambient light in the room, which causes
38 LIGHTING FOR GLAMOUR PHOTOGRAPHY