We’re not talking about red eyes caused by tiredness or over indulgence!! We’re talking about “red eye” in photos – caused when using a flash.
What you’re seeing is the bright light of the camera flash being reflected off the rear of the eye. Because the light of the flash occurs too fast for the pupil to close, the light passes into the eye, via the pupil and reflects off the back of the eyeball – it’s this reflected light that the camera then records. The main reason for the red appearance though is the amount of blood at the back of the eye.
Red eye only occurs if the flash (or any bright light source) is close the camera – in reality close to the camera lens. This is why compact cameras suffer from this phenomena the most. The ambient light level is also typically quite low when red eye occurs – so that the subjects pupils are dilated – you don’t see red eye in bright sunshine.
But how can you avoid it? Some cameras have a red eye reduction function. This fires the flash before you take the picture, causing the pupils to close – so when the actual shot is taken a fraction of a second later, there is less likelihood of red eye occurring. Another method, is to ensure that the flash doesn’t fire directly into the eyes of the subject. It depends on your equipment, but off camera flash avoids red eye completely. Also using a flash unit that allows the flash head to be angled and the light reflected from another surface not only eliminates red eye, but also allows much greater creative control.
But you don’t necessarily need expensive add on accessories! A simple piece of white card or paper can be used to deflect flash light to avoid red eye – try it out, you might be surprised at the results you can achieve.
The use of flash, reflectors and other light manipulation techniques are covered in our “Lighting Basics” course along with the use of other artificial light sources.