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Your camera is recording the reflection from the blood vessels of the retinas at the back of your subject's eyes. The phenomenon is made worse in dark conditions because your subject's irises are open wide, exposing more of the blood-rich retinas.

The phenomenon is not a function of flash as such, but rather of the angle of reflection. There is a physical law which states that the angle of reflection is equal to the angle of incidence.In other words, light bounces off a reflective surface at an angle the same as the angle the light came from. On most compact cameras, the flash is sitting right next to the lens, so the angle of incidence (where the light comes from) is essentially the same as the angle of reflection. The light bounces straight back into the lens. Since the back of the eyeball is richly supplied with blood vessels, the color of the reflection is red and you get those eerie vampire eyes.

What can you do? If you have a flash which can detach from your camera on a cord, you can remove the flash and hold it a foot or more away from the lens. The reflection will go off on the opposite angle and there will be no red eye. But most compact cameras have fixed flashtubes sitting right next to the lens. Manufacturers have devised all sorts of redeye reduction schemes. One of the most common is the rapid repeated low-power firing of the flash before the main flash. This causes the subject's irises to react by closing down, reducing the reflection from the retinas. If you don't have redeye reduction, try raising the light level in the room. If that spoils the mood, try having your subject look into a nearby lamp just before taking the picture. Your subject can also look slightly away from the lens.

If none of that works, or spoils the spontaneity, there are redeye removal pens to retouch your prints. On your computer there may be redeye removal tools. If you have any version of PhotoShop, redeye removal is a cinch.

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Most cameras have that funny pre-flash flicker before the flash; that is so that eyes have a chance to adjust, and avoid the red-eye effect. Serious amateurs and professionals avoid red eye by not having the flash so close to the axis of the lens. This is the primary cause, which unfortunately, many people can't do much about with their simpler cameras.

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โˆ™ 2011-04-22 22:34:58
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Q: What causes a red eye in a photo with a flash?
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Related Questions

Why do sometimes eyes appear red in photographs?

While taking a photo with a camera that uses a flash, sometimes the flash reflects on the eyeball, making it appear to be red. This is called 'Red-Eye.'


What are 3 modes in flash?

Auto flash, Red Eye flash, and no flash


What causes red eye in photographs?

The bright light from the flash reflects off the back of the eye where there are a great many blood vessels, this makes the light appear red as it is reflected back out of the eye.


Do wolves get red eye from camera flash?

Yes, It's the camera flash bouncing off the red blood vessels and red tissue in the back of our eye


What causes red eye?

Red eye is caused by a camera's flash reflecting off the back of your subjects eye ball's in low ambient light situations, hitting the fundus then going back into the camera. The reason for the red color is because of the large amount of blood in the choroid.


Why does a human's eye turn red a dog's eye blue and a cats eye green when a camera flashes?

What you see in an eye in a flash photo is actually the color of the backside/inside of the eye. Animals with good vision in the dark have a reflective layer behind the retina. Humans hasn't, so what you're seeing is basically blood red.


Do ducks get red eye on photos?

Animals can exhibit the same characteristic retinal reflection that causes "red eye" in people photographs. I know of no animal that reflects red, but have seen many a dog, raccoon or cat photo where the eyes were blueish or green.


Why are your eyes red in pictures?

You are actually seeing images of the retina, the layer of cells at the back of the eye. There are many blood vessels in that part of the eye, as well as a very high concentration of light receptor cells. You will note that in virtually every photo in which you see 'red eye', the photographer used a flash. The flash was probably on the camera, making it possible for light from the flash to make a reasonably direct trip from flash to retina and back to the camera. The need for the flash suggests that the ambient light level is low enough for the subjects' irises to be open. The flash and exposure happen so quickly that the iris doesn't have time to adjust by closing a little. The result is the slightly creepy effect that we call red eye. This is why most cameras today have a pre-flash option for photos of people and/or animals. A few short bursts of light cause a person's irises to close a little, and red eye is almost always avoided. If this option is not available with your camera, then placing the flash at an angle, away from the camera, may also help reduce red eye. The problem can also be fixed easily with most photo editing software packages.


Why does your rabbit have red eyes in the photo?

They have the red pigment in there eyes.....or it is because of the camera with red eye


Will a white spot in the pupil show up in every photo with retinoblastoma?

No, from what I understand, the light has to hit the cancer cells a certain way, and reflect the light back out of the eye. It apparently happens more often in low light situations with the flash on. One eye will have red eye while the other will be white or be otherwise abnormal compared to the eye with red eye.


Why does a baby have one red eye and one green when the flash goes off for a photo?

Red eye refers to the tendency of the pupil of the eye to glow red in flash photography. It is caused by light from the flash reflecting back from blood vessels in the back of the eye. The color goes green when the angle of refraction changes. It is not unusual to see one green and one red eye. The effect is worst in dim light (when you naturally want to use flash) because the pupil is dilated (expanded) more in dim light and more light enters the eye. Red eye is a common problem with small cameras that have the flash close to the lens, especially when photographing babies, pets and people with blue eyes, although it can occur at other times as well. A similar problem called "green eye" can occur along with, or instead of, the red, and is most common with pets, especially cats. Small cameras have no place else to put the flash, and most manufacturers attempt to minimize the effect by multiple flashes, the theory being that the first flash will cause the pupil to contract, and the next one will illuminate the subject for the image exposure. This is reasonably effective under some circumstances, but generally leaves a lot to be desired. The only real cure is to shoot profiles, increase the light in the room to contract the pupils, or use a flash that is positioned some distance away from the lens. Most photo editing programs such as Google's Picasa 2 (free download) have a red eye correction tool, and that is often the easiest way to deal with the problem.


How do you reduce red eye in a photograph?

If you mean how do you reduce before it even gets into the photo, then many cameras have a special setting whereby the flash goes off several times before the photo is actually taken and this cause the pupils in the eyes of those being photographed to reduce in size, which helps to stop redeye. But if you mean how do you get it out of the photo once it's there, then either you use the red eye removal tool on photo editing software, or you manually remove it using the software.


Does green eyes in a photo mean cataracts?

The effect has nothing to do with cataracts or any other malfunction of the eye. It is simply a matter of optics. Green eye or red eye is caused by the light from the flash reflecting back from blood vessels in the back of the eye. The color changes when the angle changes. It is not unusual to see one green and one red eye. The effect is worst in dim light (when you naturally want to use flash) because the pupil is dilated (expanded) more in dim light and more light enters the eye. It is caused by having the camera's flash too close to the lens, and can be minimized by using the "red eye" setting for the flash, if available. Turning on more lights in a room can help, too, as can using a lighting source that is placed away from the camera.


How do you get blue eyes on a photo?

I guess you mean remove red-eye? If not the photoshopping the colour of iris, or wearing blue contatcs. If you mean remove red-eye then vista picture viewer has an red-eye remover so do, most photo shopping software. Paint.net is one that is free to use.


What is red eye in photography?

It's how the flash bounces light into a person's eye in a certain way to make the person look like he/she has a red eye. Easily fixed in post production


Where can I find a free photo editor to take away the red eye effect on my photographs?

Kodak has a free photo editor that works great. It reduces red eye and your photographs will look fantastic. It looks like a professional has done them.


How does red eye happen on a camera?

"If an eye had absorbed all light, then this wouldn't happen. In fact, if an eye had been theoretically flawless, the red eye effect would not have existed at all. What happens when you see the red eyes on pictures, is that the flash is reflected in someone's eye. The reflection is red because of all the blood vessels inside the eye." -http://photocritic.org/red-eye-removal-reduction/


How do you fix red-eye on the Nikon COOLPIX S230?

click the red eye flash button! i will show an eye and flash sign! Here are some little software which is not as difficult ad Photoshop, that can help you to remove red eyes from your Pictures easily. http://www.downloadatoz.com/download/208217,8-foolproof-ways-to-retouch-your-photos.html


What causes red eye in swimming pools?

the devils pee


What disease has pus in eye inflamed red eyes photo phobia swelling eyelid white spot on the eyelids?

eye infection


Do cat's eyes really glow?

No. In the dark, the eyes of animals, especially animals that are nocturnal, will reflect light and look like they glow. This is the same thing that causes your eyes to "glow" red when someone takes a photo with a flash.


How do you use Red Eye Brush Tool in Photoshop?

click on red eye tool,make brush size to cover eye on your photo(make it smaller or bigger) you can do it with right click while brush tool is selected switch to red eye tool and click in center of eye.that's it.


Why is the pupil a circle?

The pupil is a hole surrounded by the iris which is the colored part of your eye. The pupil gets bigger and smaller because the iris expands or contracts to let more or less light in so you can see better. Have you ever noticed red-eye taken in a photo with flash. Well it is actually the light from the flash bouncing off of the back of your eye, if the pupil was a solid black dot it would not show the reflection coming out


Do albino's have red eyes?

No. Generally, people with albinism have blue or slate gray eyes. Some people with greater amounts of pigment have green or hazel eyes. Those with lessor amounts of pigment will have an eye color that has a reddish tint to it. Because the eye of the person with albinism has an iris which does not block out light, a flash photo of someone with albinism may show the light of the flash reflected off of the back of the eye, giving the appearance in a photograph that they have red eyes. For more info on albinism in humans check out this site: http://www.albinism.org/


How do you get of red eye editing on iPod touch?

After you've captured your photo,go to your camera roll and choose the photo you want to remove the red eye fom,then click on the 'Edit' button on the upper right of the screen,you will find a red button on the bottom of your screen (second button from right),click on that button then tap each red-eye and the red eye will be removed.After finishing click on the 'Apply' button on the upper right of your screen. Note:This only works on 4th gen. iPod.