How many times have you taken some photographs only to 
find that the people in them have glowing red eyes?  If you 
were like me, it's probably been often.  What used to 
confuse me was that it sometimes happened, and it sometimes 
didn't.  Why does this thing called "Red-eye" happen.  To 
answer this we have to first take a closer look at the eye 
  The eye is a marvelous piece of engineering (I'm a 
Creationist, even Darwin couldn't explain how eyes could 
develop by random chance).  I will try to explain the eye 
in simple terms, although it is very complex.  The eye is 
shaped like a ball, filled with clear liquid.  At the front 
is a lens that refracts (bends) light so it falls into 
focus at the back of the eye.  In front of the lens is the 
iris, which is a diaphram that controls the amount of light 
that enters the eye.  It's opening gets smaller in brighter 
light to allow less light into the eye.  At the back of the 
eye is the retina, a mass of light-sensitive nerves that 
actually "capture" the image the eye sees and send it to 
the brain for interpretation. 
  Behind the retina is a reflective layer that bounces 
light that passes through the retina back again.  Light 
that enters the eye either hits the retina or is reflected 
off the back of the eye; which has a second chance to hit 
the retina.  Thus any light that enters the eye has two 
chances to strike the retina and produce and image.  It's 
almost like taking the net off a hockey goal.  Now the puck 
would have two chances to go through the goal.  If someone 
made a shot and missed, it just might bounce off the boards 
behind the goal and go through the net in the opposite 
direction.  This reflective layer helps out a great deal in 
low-light situations.  This feature is greatly enhanced in 
some animals, such as cat's, which have excellent night 

  When you see a person's eye glowing in a picture, you are 
actually seeing the light reflected off the back of their 
eye.  Why is it red?  Because the retina is red.  A 
person's pupil is normally black because there is no light 
inside the eye, and thus it is black.  It would be like 
cutting a small hole into the side of a closed box.  The 
hole would appear dark because it's dark inside the box.  
However suppose you would put a piece of aluminum foil or a 
mirror inside the box opposite the hole. If you would shine 
a flashlight at the hole from the outside, the light would 
bounce off the reflective surface and come back out the 
hole, causing it to glow.  This is what is happening when 
you see people's eyes glowing in pictures. 

  There are 3 ways to reduce or eliminate "red-eye" from 
photographs.  The first way is to move the electronic flash 
farther from the camera lens.  When the light is reflected 
off the back of the eye, it exits the eye in a cone shape.  
The smallest part of the cone is at the eye, and it becomes 
larger the farther from the eye it gets.  Imagine putting a 
hole in one side of a closed box and putting a light in it. 
If you would point the hole at a wall, it would produce a 
circle of light.  If you move the box away from the wall, 
the circle of light would become bigger.  The farther away 
from the wall you move the box, the bigger the circle of 
light would become.  Now, combine this information with the 
fact that light is reflected BACK TO IT'S SOURCE.  So the 
light from electronic flash is reflected BACK to the 
electronic flash (in a cone that gets bigger the farther 
from the eye that you get).  If you have a camera with an 
electronic flash that is built into the camera body, when 
the light is reflected back to the flash, it also hits the 
lens, and you get red-eye.  If you have a hotshoe, you can 
put an electronic flash on the top of your camera.  By 
doing that, you put more distance between the flash and the 
camera lens.  When the light is reflected toward the flash, 
the lens has more of a chance to be out of the cone of 
light because it is farther away from the flash.

  The second way to reduce or eliminate red-eye is closely 
related to the first.  Try to move closer to your subject. 
Since the light that is reflected from the eye is cone 
shaped, the closer you move to your subject, the smaller 
the cone is.  The light reflected back towards the flash 
may hit the flash only at 6 feet.  But at 20 feet, the cone 
of light would have expanded to not only hit the flash, but 
the camera lens as well, causing red-eye.

  The third way to reduce red-eye is to raise the level of 
light in the room by turning on more lights.  By doing 
this, the iris of the eye closes into a smaller hole.  
Since the eye is now admitting less light into the eye 
because of the additional light, it will also let less 
light from the flash into the eye, and also less light to 
reflect off the back of the eye.

  To sum it all up, to reduce, or hopefully eliminate 

       1) Move your flash farther from your camera lens.
       2) Move closer to your subject.
       3) Raise the level of natural light.  

  An alternative way, when all else fails, is to remove 
red-eye from the pictures themselves.  If you use a fine 
felt-tip pen (permanent works best) you can just cover over 
the red irises to make them black.  You should practice on 
prints that you do not care about until you become good 
enough to trust your skill on prints that you do care 


Joseph Miller
Lebanon, PA