Red-Eye: Its causes and how to deal with it By Wade Herman, Tampa PC Users Group wherman1@tampabay.rr.com

I think we are all familiar with that picture that is lovely except for the horrible red spot in the center of the subject’s eyes, Red-Eye. The first thing to note is that it only occurs in flash pictures and the darker the room the more pronounced the effect. Fortunately, digital photo editing programs can greatly reduce the problem, but it is still best to eliminate the problem at the source when possible.

The effect is caused by the light from the flash reflecting off of the rear of the eye, the retina, which contains translucent blood carrying capillaries. Thus, the reflected light is red. The reflected light is passed back out of the eye and imaged by the camera. In dark surroundings, the iris of the eye, like that of the camera, opens to pass more light, thus the more pronounced the effect. Professional photographers deal with the problem by offsetting the flash source 6-10 inches from the plane of the camera lens. In this case, the reflected red light is offset so it does not pass through the camera lens. The amateur photographer does not want to carry around such a bulky contraption, so another solution has been developed. Unfortunately, it does not work very effectively. In this case just before taking the picture the camera sends out one or more preflashes in hopes of making the eye’s iris small enough that little light is passed back to the camera even though the flash and lens are very nearly on the same axis. Unfortunately, the preflashes are seldom strong enough or long enough to cause the iris to constrict before the main flash and may cause the person to blink at the wrong time. This feature often does considerably reduce battery life but little else.

What can the photographer do? Only use the flash when there is no other way to sufficiently light the subject. Turn on additional lights and open drapes. Remove lamp shades from lamps out of view of the camera. If you must use the flash, place a bright light source in the direction the subject will be looking, thus constricting the subject’s iris. Have the subject look at an object off camera.

If all of this fails to give acceptable results, then obtain a retouching program that has a good Red-Eye Retouching feature. u