Red Eye Reduction
The phenomenon of red eye occurs when the flash is incident on the eyes and gets reflected back by a dilated pupil.
The eye’s pupil dilates and shrinks as per the need for an optimum eye sight. In case there is low light, the pupil dilates to let in more light, while it shrinks if there is excess light.
When, in a low light condition, a flash is fired, the pupil doesn’t get enough time to shrink and the light illuminates the retina, which is captured by the camera. This causes the red eye effect. The following photo of Nikhila exhibits the issue.
The above shot was taken at a low light condition with flash being fired directly at her.
In the following shot, also in a low light condition, the flash was fired with the Red Eye Reduction mode enabled.
What this mode does is, in Nikon cameras, it lets out a strong light from a bulb at the subject so that their pupils shrink, and then the photo is taken; while in Canon cameras, the flash strobes and then the actual shot is taken, giving similar results.
Red Eye is not an issue if there is already a sustained light incident on your subject, as evident from the following shot of Milind Soman.
So, while shooting in a low light condition, if you are forced to use flash, it is useful to have a red eye reduction mode switched on, or have some sort of light on your subject’s face.
The Red Eye phenomenon has a medical aspect to it too. In case, in any of your photos, you notice that a person is exhibiting red eye in just one of the eyes, do recommend a visit to the doctors to that person, for it may be a case of leukocoria.
Let me know about your brushes with red eye in the comments.
Last time, R was for Rear Curtain.