Sunday 23 August 2009

People Pictures: How to Really Get Rid of the Dreaded Red Eye

By Craig Stoner

For years now, film and digital camera manufacturers have been inflicting red-eye reduction settings on their customers. Its a series of bright, strobing flashes that's not only annoying to the people you're photographing, but doesn't even work very well.

What causes red eye? In a dimly lit room, the subject's pupil opens, revealing more of the retina. The back of the retina has blood vessels over it, hence the red colour that is caused when the light bounces of the back of the eye.

On cameras where the flash is close to the camera lens (as it almost always is), the light from the flash shines through the dilated pupil, bounces off the retina, and reflects as a red circle directly back into the lens. (the same thing happens to animals, too, except that the colour is sometimes green or orange instead of red.)

The solution is to move the flash away from the camera lens or use bounce flash. That way, the reflection from the retina doesn't bounce directly back at the camera. But on a camera that fits in your pocket, its not practical to achieve much separation of flash and lens.

Since camera manufacturers couldn't move the flash away, they went to Plan B: firing the flash just before the shutter snaps, in theory contracting the subjects' pupils, thereby revealing less retina.

Unfortunately, it doesn't work very well, and you may end up with red eye anyway. The other problem is that some people see the pre-flash as the picture being taken and then move while the shutter is open. Not a good result.

Basically you have three ways out of red eye. You can turn up the lights to help contract the subjects pupils. You could also use a camera that accepts an external, detachable flash. And if none of that works, remember that you can edit out red eye on your computer, using for example, the red eye reduction tools offered in many photo editing programs.

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