[CT]

To avoid red eye in your flash shots, it helps to understand what causes it in the first place. The retina right at the back of the eye is fed by lots of tiny little blood vessels, and if a bright light is shone directly into the eye it's these blood vessels which cause the redeye which is the bane of so many flash shots in subdued light. It's often more pronounced in the young and that's just as true of animals too.

When we're indoors under even quite strong artificial light, our pupils dilate and open up to admit more light, and are far more open than they would be outdoors under good light. It's under just these conditions of course that the vast majority of flash shots are taken. The absolutely worst scenario is to be using a little compact camera where the flash is down close to the axis of the lens, as the flash goes directly into the eye and bounces back to your sensor or film having picked up all that red light from the retina. The further you can get your flash head away from the axis of the lens so that the flash enters the eye at a less direct angle, the better,

Modern DSLRs are tending to get built-in flashes which now pop up and sit a little higher than they used to, and it's a big help in reducing the problem, but an accessory flashgun is even better, as they set the flash head higher still. Even then it's no guarantee that you wont get slight red eye under certain conditions. Either use a flash extension cord from your camera to get the flashgun right away from the axis of the lens, or if you have to use a flashgun mounted in the hotshoe, then swivel the head and bounce the flash to be really safe.

Red eye is seldom any problem in really good light, as our pupils contract sufficiently to counter the problem. You can also reduce the problem considerably by getting your subjects to look to one side of, rather than directly at the lens.

People are more aware of red eye than they used to be, and to combat the problem, manufacturers now incorporate various red eye reduction systems into cameras and flashguns. These usually take the form of small pre-flashes which are supposed to cause the pupil to close down before the main flash fires. They are less than useless in my experience as some people are hopeless blinkers anticipating the camera flash anyway, and often the pre-flash just causes your subjects to be caught blinking when the actual shot is taken.

Photo editing packages often have a red eye correction facility now, and some are better than others, but you'll never get more natural looking eyes than you will by avoiding the problem in the first place. So to recap, if you're shooting with flash indoors, even under good artificial light, then think about the possibility of red eye. Outdoors it's seldom a problem, unless of course, it's dark.

[Gary Bagshawe]

It is also a bigger problem when using a telephoto lens when you are a good distance away from your subject.