What exactly cause red-eye within a photo? why does it appear on some people and not
why does it appear on some people and not on others within the same photo?
Answers:
The answer you received is correct. When a subject looks directly into the camera that is when you will experience the red eye effect. (thus, why some subjects within a pic will have red eye and others won't) Have your subjects look basically above or to the right or left of the camera.
The closer the persons eye is to the axis of the lens, the more pronounced the redeye effect. So those on the edges of the shot will not show dreaded redeye.
You may own noticed that pro photogs shoot using an external flash ... raise the flash just a few inches does the trick. P&S cameras usually enjoy a redeye reduction portion to help run down this.
Red eye is the reflection of the flash of the camera on the blood rich retina of the eye.
As previous populace have said, if the subject is looking straight at the camera surrounded by line next to the plane of the lens you get maximum red eye.
The effect vary depending on the individual. Sometimes subjects aren't looking directly at the camera so you won't get the effect. Some folks have smaller number blood supply than others so the effect may be less. And some race, depending on the lighting conditions prevalent at the time, may have a constricted iris which would also mitigate or prevent the effect.
When you're doing a group shot the fundamental reason it's not global is that not everyone is looking directly at the camera and as a result they don't produce the effect.
The simplest way to avoid red eye is to ask your subject to look away from the camera. Another method is to hold the flash away from the camera but of course that's out of the question with a built contained by flash. Bounce flash can also mitigate red eye since the light of the flash doesn't directly enter the eye.
Manufacturers attain around it with what they bid red eye protection in their flashes. The opinion is that if you dose the eye with a bright flash the iris will constrict adequate so that when the flash fires the red eye is prevented. That's the theory. So they design the flash to blast two or three bright short flashes up to that time finally opening the shutter and taknig the picture.
Sometimes that does contained by fact work assuming that the iris of your subject is snatched enough within closing. More often than not it fail to eliminate red eye. The other problem beside this solution is that often the subject assumes the picture have been taken and turns away past the shutter opens. In that instance you've cured the red eye problem but you finishing up with a picture specifically less than just the thing.
I hope this answers your question.
Red-eye surrounded by photos is a flash phenomenon. It¡¯s very unlikely you¡¯ll encounter it using sunlight, or available muted only when shooting indoors.
The pupil of a person¡¯s eye, even though it appears to be black when we outlook it, is actually clear. Since the inside of the eyeball is generally never illuminated, we see it as a small black circle. But within some flash photos, if the flash is close to the lens of the camera, its illumination sends a burst of street lamp right through to the rear of the inside of the subject¡¯s eyeball. The retina of your subject¡¯s eyes is rich contained by red blood vessels, and this produces the bright red color we see contained by the pictures.
If the flash is close enough to the lens, the buoyant not only enter your subject¡¯s inner eye, but can then echo straight back out and truly be recorded by the camera. With the retina contained by your subject¡¯s eye now fully illuminate, you get the tell-tale bright red shine that we all presently know as red-eye.
Follow the link below if you want to know how to avoid red-eye surrounded by flash photos:
http://dc-digital-camera.blogspot.com/20... Because some inhabitants have evil demons inside and some ethnic group don't.