What causes the red eye effect in photos?

Answer 1

Red eye is caused by the pupil, or small black circle at the center of your eye. When you are in certain light, usually indoor lighting, your pupils are larger to allow more light into your eyes and give your retina more light to work with. However, when the flash occurs from a camera, the light reveals the back of your eye to the camera lense, causing the red we see. Red eye reducing cameras use a number of ways to prevent this, such as flashing a few times, causing your pupil to contract and shrink before the lense actually records the photograph.

Incidentally, low light in a restaurant is used to cause your pupils to be enlarged, which is a type of body language, believe it or not. When your pupils are enlarged, naturally and not necessarily because of low light, it means you are happy with what you see, including the people you are looking at. In return, that person who is looking back at you subconsciously sees your pupils enlarged and recognizes that you like them. Therefore, by lowering the light in a restaurant during dinner, they are encouraging a relaxing and pleasant atmosphere, especially for couples.

Answer 2

Red eye results when the strobe's light is reflected from the eye's retina (in the back of the eye); it really doesn't matter what color eyes the subjects have (although it is more common with subjects that have light colored eyes, and also with animals that look directly into the camera lens). This is because the strobe and the camera lens are so close together and the strobe light reflects back into the lens.

One way to avoid this if the camera has a built-in strobe.
is to have the subjects look slightly over your shoulder (I tell them to look at my ears). This kills the spontaneity of the photos, though.

Another way to avoid the red eye effect is to use a diffuser on the strobe. I made one out of an almost clear film cartridge plastic container; I cut the bottom out with a utility knife, then cut the hollow barrel so that I can open it into a "C" and I place it on the built-in strobe of my two Nikon N80 cameras. I keep this "diffuser" in my everyday walking around camera bag with my two N80 cameras.

You can also avoid using the strobe flash but that isn't always feasible. Or, you can NOT use the strobe and use a fast lens, like f/1.4 but that would certainly limit your creativity since f/1.4 or even f/1.8 lenses are primes.

The one way that I've found that works all the time for me is to use an "L" bracket with my strobes on my two Nikon F5 cameras, which I use for weddings, graduations, and environmental or on-site portraits. This causes the light beam from the strobes to be off center so that the reflection is thrown back elsewhere and not directly back to the camera lens.

A feasible alternative for those with strobe lights that attach to the camera's hotshoe, however, is to use a strobe that tilts or swivels toward the ceiling, and you can bounce the light from the white-colored ceiling onto your subjects; this prevents the light from being reflected back from the back of the eyes to the lens.

I hope this helps. Good luck and best wishes.

Answer 3

As other answers have told you it is caused by light entering the eye, bouncing off the retina and returning to the camera as red light. The lighter the color of your pupil the easier this effect will happen.

One reason for it becoming so prevalent recently is how close the flash is to the lens in small modern cameras, this gives nearly a perfect 180º return path and makes the problem worse. Larger professional cameras have large external flashes sometimes not even mounted on the camera to alleviate this problem.

Answer 4

Redeye happens when light from the flash goes into someone's open eye and reflects off the back of the eyeball (the retina). In order to prevent it, you have to make people's irises contract so the hole is smaller. That's why a red eye reducing flash has a couple early flashes (so people's eyes close up) before the picture is taken.

Answer 5

When a camera flash hits the eyes, the color of the blood vessels in the back of the eyes is being captured by the camera. Hence, the red eye.

Answer 6

If I am not mistaken it is the color of your iris. I see a lot of people with light eyes having that issue.

Answer 7

The subject is possessed

Answer 8

not sure http://en.wikipedia.org/wiki/Red-eye_effect