This is what causes red-eye in photographs

One of the problems many new photographers face is red-eye. Using your camera’s built in flash in dark environments is usually the cause. But, have you ever wondered what exactly is the reason for this phenomenon?

This video from SciShow explains the problem with some easy to understand science. It also talks about some of the ways digital cameras try to get around creating red-eye and ways you can fix the issue yourself.

The obvious solution for more experienced photographers is to get the flash away from the lens. Once you increase the angle at which the light hits the eye relative to your lens, the problem goes away. But for those who haven’t yet invested in flash gear, there are a few tips.

The first is the red-eye reduction feature of your camera. It works by sending out several pre-flashes before the main exposure. This tricks your eye into thinking it’s bright, closing down your pupil and reducing the risk of light reflecting off the back of the eye. It’s helpful in some circumstances, but I’ve it’s not always so successful.

Brightening the environment in which you’re photographing your subject will also help. This will naturally make your subject’s pupils smaller, having the same effect. Your flash also won’t need to put out as much light to get a good exposure, further reducing the effect.

The other option suggested is to have your subject turned slightly away from the camera, but this doesn’t really work if you want them looking at the camera.

For photographers, this phenomenon is an annoyance, but for medical purposes it can help to diagnose certain eye conditions.

If you must use flash, the best option is still generally to remove the light source from the next to the camera’s lens. If there’s no choice but to use a flash on the hotshoe, bouncing it off a wall or ceiling will almost always eliminate the issue.

Of course, you can always try shooting without flash, too.

Is red-eye something that happens to you often? Do you try to fix it right there and take another shot? Or do you fix it in post? What other tips do you have for avoiding red-eye? Let us know in the comments.