WHY do people have red eyes in flash photographs?

Answer 1

The light of the flash occurs too fast for the iris of the eye to close the pupil. Light is focused onto the blood-rich retina at the back of the eye and the image of the illuminated retina is transmitted to the camera resulting in the red appearance of the eye on the photo. This principle is used in fundoscopy (an eye examination used to examine the retina by using an opthalmoscope), wherein a positve ROR or Red reflex is a normal finding.

The effect is generally more pronounced in people with grey or blue eyes and in children. This is because pale irises have less melanin in them and so allow more light to pass through to the retina. Children, despite superficial appearances, do not have larger pupils but their pupils are more reactive to light and are able to open to the fullest extent in low light conditions.

Answer 2

As others have stated, the flash bounces off retina in the back of the eye, and the flash is so fast that the iris doesn't have time to contract which makes the effect worse. - But there is another reason for the red eye effect: Namely a flash that is very close to the lens, because the light reflects back directly toward its source - so a lens that is very near by will pick up the red from the retina. If you imagine that the distance between the lens and the flash forms one side of a triangle (with the other two sides of the triangle consisting of the distance from the lens to the eye and from the flash to the eye, you can see how the effect iwill be most pronounced, if the photographer is relatively far from the subject. One way to get rid of the red eye effect is to use a flash that is a foot or more off the camera, pointed lightly downward at an angle.

Answer 3

The 'red eye' effect is caused by light reflecting off the retina and back through the iris (pupil) of the eye. The blood vessels in the eye cause the red color.

This is a common problem with flashes built into the camera. Because they are almost directly inline with the lens, the line of the light entering the eye is practically the same as the light being reflected back when the subject is looking directly at the camera.

Many cameras have a 'Red Eye Reduction' mode. This produces a flash just before the exposure which makes the subjects pupil get smaller and this means less light less light enters the eye to be reflected back. This reduces red eye, but does not always eliminate it.

The higher the ambient light (the light without the flash) the less chance there is of red eye because the pupils are smaller to begin with.

Vance

Answer 4

That's called red-eye effect. And it happens cause the flash flashes too fast for the eye's pupil to close, so when it takes the picture you can see how the pupil appears really big. That shows up in a red color when the picture is finished. I'm not sure why it makes them look red but maybe you can find out in the link below! :)

Answer 5

Everyone has given you a pretty good description of why red eye happens. To keep from getting it when you use your flash and you don't have red reduction on your camera have everyone look slight to the left of right of the camera. It will reduce or eliminate the affect.

Answer 6

red eye effect is caused by the flash light passing through the eye,since the does not restrict the light rays.this is more a happening with kids than grownups because of their age,and their younger eyes,than the grownups.

Answer 7

it depends on there eye colour if its blue or something light when the camera flashes the eyes turn red

Answer 8

Have you already used Eye Floaters No More mechanism. Visit here : http://EyeFloaters.NatureHomeCure.com . This might clearly explain one and all!

Answer 9

the flash reflects off of the retina of the eyeball
go to howstuffworks.com to see what I mean

Answer 10

Because they are actually rabbits cleverly disguised as human beings.