What is Red Eye?
When people are photographed in low light conditions with on camera flash as the main light source illuminating the subject, their eyes appear to glow red in the photographs, giving a ghostly appearance. This is called Red Eye Effect in photography.
 |
| Photo Courtesy Wikipedia |
What Causes Red Eye Effect?
When a subject is illuminated with light originating from the same axis as that of the lens; it causes the light to reflect directly back on to the lens. When photographing people in low light, their pupils will be wide open to gather as much light as possible to see clearly and when a flash is triggered, the light from the flash enters the eyes and illuminates the inside of the eye which is filled with numerous blood vessels this is what we see as Red Eye.
 |
| Red Eye Effect When Photographed With On Camera Flash |
Does Red Eye Effect Occur when Photographing All Living Things
The answer is NO. Some animals, especially those who are equipped to see in the dark have a special reflective layer in their retina called the tapetum licidum (Humans don't have this Dogs, Cats, Deer etc do). The purpose of tapetum licidum is to act like a mirror reflecting the maximum amount of light falling on it back to the retina so as to enhance night vision. So when light from the flash falls on such eyes the tapetum lucidum layer reflects it back, like a mirror does and therefore NO RED EYE, their eyes just appear like glowing bright white spots.
How to Avoid Red Eye Effect in Photographs?
- Flash being responsible for causing red eye, taking pictures without flash, by increasing the ambient lighting, using wider lens apertures, reducing the shutter speed, increasing ISO etc could solve the issue.
- Using a Dedicated Hot Shoe Flash instead of the Pop Up Flash could reduce the chances of red eye.
 |
| Red eye effect when a dedicated flash is used instead of the built in flash |
- Tele photo lenses with increased flash to subject distance are more prone to red eye due to their narrow angle of reflection.
 |
| Red Eye Effect When Using Long Lens |
- Diffusing or bouncing the flash instead of direct flash would help eliminate red eye.
- Changing the angle of light away from the lens angle by taking the flash off camera or by using a professional flash bracket will help avoid red eye effect.
- Make your subject look away from the camera instead of directly looking into it.
- Use a UV filter when photographing people who use contact lens.
- Make use of the red eye reduction feature if your camera has it (Most modern camera’s do).
If all of the above fail or if you were too lazy to have taken care to avoid it while shooting, you could easily fix it in post processing.
In the next article we will discuss about Photography - Tips For Beginners - Elements That Make a Great Photograph