How a Flash Turns Eyes Red
All digital cameras come with a built-in flash. (If I’m wrong and you know of a digital camera built in the Outer Hebrides that has
no flash, please write. I can’t wait.) Built-in flash—either the type that pops up above the lens or the kind that sits flush with the front
of smaller cameras—is too weak to light up a subject more than a few yards away. This is fine for birthday candle blowing, and
it’s the simplest way to usefill flash. But built-in flash has a serious flaw: It’s built in and, often, in exactly the wrong place.
(Directly over your lens is not the most intelligent place to mount a flash.) Aflash attachment—or, more accurately, I suppose,
detachable flash—gives you more light and more ways to use that light in your picture.
92 PART 2 HOW DIGITAL CAMERAS CAPTURE IMAGES
Red Eye: Getting the Red In...
The light from the flash passes through the clear
liquid that fills the eye and strikes the retina at
the back of the eye. The retina is rich with blood
vessels that give it a bright red coloration. Light
from the flash reflects off the red retina and trav-
els back out the wide-open iris to be captured
by the image sensor (or film). The result: Your
subject looks possessed by a demon.2
1 A flash mounted directly inline with the axis of a lens fires as the picture is taken. The light
from the flash enters the eyes of the subject through his irises. Because the setting is dark
enough to require a flash, chances are it’s dark enough to cause the irises to open as wide
as they can.)Other Ways to Reduce Red Eye
◆ Have the subject look away from the camera.
◆ Hold a flash gun, attached to the camera with a cable, away from the
camera.
◆ Bounce the light from the flash off the walls or ceiling.
◆ Use an image editor such as Photoshop or Paint Shop Pro to cover up the
red portion of the eye.