Red eyes effect - the root cause and how to avoid it
Red eyes effect - the root cause and how to avoid it | ||
|
All digital cameras come with a built-in flash. 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 use fill 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. A flash attachment—or, more accurately, I suppose, detachable flash—gives you more light and more ways to use that light in your picture. 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 travels back out the wide-open iris to be captured by the image sensor (or film). The result: Your subject looks possessed by a demon. 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. Some cameras minimize red eye by first shooting a short flash without taking a picture. This short flash causes the subject's irises to reflexively contract. This short flash is followed by one matched to the opening of the camera's shutter. Light from the second flash is largely blocked by the nearly closed iris so that little light enters the eyeball and still less is reflected off the retina back to the camera. Ways to Reduce Red Eye
| ||