Red Eye

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Posted By
Peter Rawlings
May 2, 2005
Views
389
Replies
17
Status
Closed
How is the Red Eye tool accessed in CS?.Anyone Please.

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GV
Gerard Verhoef
May 2, 2005
Only in CS2:

It’s one of the tools in the same little square as the healing brush

Gerard
"Peter Rawlings" wrote in message
How is the Red Eye tool accessed in CS?.Anyone Please.
PR
Peter Rawlings
May 2, 2005
Sorry.I should have said CS2.
"Peter Rawlings" wrote in message
How is the Red Eye tool accessed in CS?.Anyone Please.
PR
Peter Rawlings
May 2, 2005
Thanks.
"Gerard Verhoef" wrote in message
Only in CS2:

It’s one of the tools in the same little square as the healing brush
Gerard
"Peter Rawlings" wrote in message
How is the Red Eye tool accessed in CS?.Anyone Please.

CF
Craig Flory
May 2, 2005
Has anyone ever explained why red eye happens ? When the flash is too close to the lens light goes through the outside of the eye and lights up the small blood vessels and that is why it looks red. Professionals, like myself, don’t get it because we have the flash at least a foot or more above the lens. I know this is not what you asked … but sometimes knowing why something happens can be a help.

Craig Flory
M
Mark
May 2, 2005
"Craig Flory" wrote in message
Has anyone ever explained why red eye happens ? When the flash is too close to the lens light goes through the outside of the eye and lights up the small blood vessels and that is why it looks red. Professionals, like myself, don’t get it because we have the flash at least a foot or more above
the lens. I know this is not what you asked … but sometimes knowing why something happens can be a help.

Craig Flory

Is it really the small blood vessels or the passage of light thru the pupil and reflecting back that causes red eye???? And it isn’t "really" necessary to have the flash a "foot or more" above the lens–2-3 inches for a good camera mounted flash that has the correct angle is sufficient to do the trick….

Mark
H
Hecate
May 2, 2005
On Mon, 02 May 2005 21:22:33 GMT, "Mark" wrote:

Is it really the small blood vessels or the passage of light thru the pupil and reflecting back that causes red eye????

It’s the reflection of blood vessels at the back of the eye.

And it isn’t "really" necessary
to have the flash a "foot or more" above the lens–2-3 inches for a good camera mounted flash that has the correct angle is sufficient to do the trick….
Any flash mounted directly on the camera above the lens is likely to produce red eye. Doesn’t matter how good the flash is…



Hecate – The Real One

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you don’t have, to impress people you don’t like…
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Jon Fredrik Stuestoel
May 2, 2005
"Mark" wrote in message
"Craig Flory" wrote in message
Has anyone ever explained why red eye happens ? When the flash is too close to the lens light goes through the outside of the eye and lights
up
the small blood vessels and that is why it looks red. Professionals,
like
myself, don’t get it because we have the flash at least a foot or more above
the lens. I know this is not what you asked … but sometimes knowing
why
something happens can be a help.

Craig Flory

Is it really the small blood vessels or the passage of light thru the
pupil
and reflecting back that causes red eye???? And it isn’t "really"
necessary
to have the flash a "foot or more" above the lens–2-3 inches for a good camera mounted flash that has the correct angle is sufficient to do the trick….

Mark

Red eyes are caused by light emitted from the flash entering through the pupil (opening of the iris) reflected from the retina (or actually choroidea which is red, mostly due to blood vessels), and hitting your film/digital sensor though the lens of the camera. It is the angle of the axes of light that counts. If you are shooting from long distance, you need more space between the lens and the flash than if you are shooting close-up.

Regards


Jon Fredrik Stuestol
R
Roy
May 2, 2005
"Jon Fredrik Stuestoel" wrote in message
"Mark" wrote in message
"Craig Flory" wrote in message
Has anyone ever explained why red eye happens ? When the flash is too close to the lens light goes through the outside of the eye and lights
up
the small blood vessels and that is why it looks red. Professionals,
like
myself, don’t get it because we have the flash at least a foot or more above
the lens. I know this is not what you asked … but sometimes knowing
why
something happens can be a help.

Craig Flory

Is it really the small blood vessels or the passage of light thru the
pupil
and reflecting back that causes red eye???? And it isn’t "really"
necessary
to have the flash a "foot or more" above the lens–2-3 inches for a good camera mounted flash that has the correct angle is sufficient to do the trick….

Mark

Red eyes are caused by light emitted from the flash entering through the pupil (opening of the iris) reflected from the retina (or actually choroidea
which is red, mostly due to blood vessels), and hitting your film/digital sensor though the lens of the camera. It is the angle of the axes of light that counts. If you are shooting from long distance, you need more space between the lens and the flash than if you are shooting close-up.
Regards


Jon Fredrik Stuestol

Red Eye is not due to blood vessels. All mamals have red blood, but some give Green Eye when the Flash is too close to the lens.

It has to be a reflection from somepart within our eyes.

Roy G
S
Scrufff
May 3, 2005
The red-eye in your images is caused by light reflecting off the retina, which is a fine network of nerves in the back of the eye, an area rich in blood. Although the retina is not normally visible, if the flash is on the same plane as the lens, the light bounces directly back into the lens and the retina becomes visible in the photo, causing red-eye. This has become more common with smaller compact digital cameras where the flash is very close to the lens. Have you ever noticed that a professional photographer’s flash is mounted high on the camera? Sometimes a pro will even take it off the camera.

The fact that the pupil is expanded to its maximum under most flash conditions only exaggerates the problem. Cameras with red-eye reduction will fire the flash two or more times: the first time to constrict the pupils, the second time to expose the image.

Red-eye-reduction software keys on the red and applies a correction. The correction is usually made by desaturating the color in the area. This will appear more natural than if it were filled with black or matched to the surrounding color of the iris (both treatments tend to make your subject look like an alien).

http://reviews.cnet.com/5208-6130-0.html?forumID=7&threa dID=10801&messageID=123998
S
SamMan
May 3, 2005
"Gerard Verhoef" wrote in message
Only in CS2:

It’s one of the tools in the same little square as the healing brush
Gerard

It still doesn’t work as well as using the Channels pallet… IMHO.


SamMan
Rip it to reply
JF
Jon Fredrik Stuestoel
May 3, 2005
"Roy" wrote in message
"Jon Fredrik Stuestoel" wrote in message
Red eyes are caused by light emitted from the flash entering through the pupil (opening of the iris) reflected from the retina (or actually choroidea
which is red, mostly due to blood vessels), and hitting your
film/digital
sensor though the lens of the camera. It is the angle of the axes of
light
that counts. If you are shooting from long distance, you need more space between the lens and the flash than if you are shooting close-up.
Regards


Jon Fredrik Stuestol

Red Eye is not due to blood vessels. All mamals have red blood, but some give Green Eye when the Flash is too close to the lens.

It has to be a reflection from somepart within our eyes.
Roy G

As I said, red eyes are caused by reflections from choroidea. Choroidea is red, mostly because of blood vessels. Anyone using an ophtalmoscope looking into someones eyes will be able to see for themselves. Some animals have another anatomical structure reflecting light differently in the eyes, called septum pellucidum. This gives different reflections.

I am not very much into veterinary medicine. For anatomical differences go search on the web.

Regards


Jon Fredrik Stuestol
JF
Jon Fredrik Stuestoel
May 3, 2005
"Jon Fredrik Stuestoel" wrote in message

As I said, red eyes are caused by reflections from choroidea. Choroidea is red, mostly because of blood vessels. Anyone using an ophtalmoscope
looking
into someones eyes will be able to see for themselves. Some animals have another anatomical structure reflecting light differently in the eyes, called septum pellucidum. This gives different reflections.

Sorry, late night here. The reflective layer is called "tapetum lucidum". "Septum pellucidum" is something completely different. It is the thin layer separating the tho lateral ventricles of the brain. My mistake.

For more info on "tapetum lucidum", see:
http://www.sciam.com/askexpert_question.cfm?articleID=000995 E3-6315-1C72-9EB7809EC588F2D7

Short info on "septum pellucidum":
http://www.sci.uidaho.edu/med532/septum.htm

Regards,


Jon Fredrik Stuestol
PF
Paul Furman
May 3, 2005
Jon Fredrik Stuestoel wrote:

"Roy" wrote in message
Red Eye is not due to blood vessels. All mamals have red blood, but some give Green Eye when the Flash is too close to the lens.

It has to be a reflection from somepart within our eyes.
Roy G

As I said, red eyes are caused by reflections from choroidea. Choroidea is red, mostly because of blood vessels. Anyone using an ophtalmoscope looking into someones eyes will be able to see for themselves. Some animals have another anatomical structure reflecting light differently in the eyes, called septum pellucidum. This gives different reflections.
I am not very much into veterinary medicine. For anatomical differences go search on the web.

First result
http://www.google.com/search?hl=en&q=red-eye+animals&amp ;btnG=Google+Search http://dpfwiw.com/red-eye.htm
Has a good explanation of the night-vision reflective double bounce-back layer on many animals. And covers the other red-eye topics well.

They also emphasize that it is better prevented than photoshopped!

5 degree angle seems to be the magic limit for prevention. The angle between two adjacent knuckles at arm’s length or 6 inches separation at 6-feet, 10 inches at 10 feet, etc, roughly.


Paul Furman
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Colin D
May 3, 2005
Gerard Verhoef wrote:
Only in CS2:

It’s one of the tools in the same little square as the healing brush
Gerard
"Peter Rawlings" wrote in message
How is the Red Eye tool accessed in CS?.Anyone Please.

Not so; it’s in Elements 3 as well.

Colin
CD
Colin D
May 3, 2005
Mark wrote:
"Craig Flory" wrote in message
Has anyone ever explained why red eye happens ? When the flash is too close to the lens light goes through the outside of the eye and lights up the small blood vessels and that is why it looks red. Professionals, like myself, don’t get it because we have the flash at least a foot or more above
the lens. I know this is not what you asked … but sometimes knowing why something happens can be a help.

Craig Flory

Is it really the small blood vessels or the passage of light thru the pupil and reflecting back that causes red eye???? And it isn’t "really" necessary to have the flash a "foot or more" above the lens–2-3 inches for a good camera mounted flash that has the correct angle is sufficient to do the trick….

Mark

I don’t think it’s due to blood vessels – unless cats and dogs have green blood!

Red-eye is caused when the angle between the flash and the lens subtended at the eye is less than the critical angle. A small camera with flash an inch or two above the lens can be ok at close range, but further back, the subtended flash-lens angle reaches the critical, and red-eye results. It’s also a function of pupil diameter. Children with wide-open pupils show red-eye where an adult with smaller pupils doesn’t.

The answer is indeed to get the flash away from the lens, and an additional benefit of that is to improve the modelling by providing some shadows. Compact cameras can’t do this, of course.

Colin
R
Roy
May 3, 2005
"Peter Rawlings" wrote in message
How is the Red Eye tool accessed in CS?.Anyone Please.

Further to my previous posting, I meant to add that my dog has a cataract in one eye, and the bright reflections from that eye, have a hole in the centre of them, which is even more disturbing.

Red eye is better avoided by the sensible location of the Flash Gun, upwards and sideways on a Flash Bracket.

Roy G
P
patrick
May 8, 2005
"Mark" wrote in message
"Craig Flory" wrote in message
Has anyone ever explained why red eye happens ? When the flash is too close to the lens light goes through the outside of the eye and lights up the small blood vessels and that is why it looks red. Professionals, like myself, don’t get it because we have the flash at least a foot or more above
the lens. I know this is not what you asked … but sometimes knowing why something happens can be a help.

Craig Flory

Is it really the small blood vessels or the passage of light thru the pupil and reflecting back that causes red eye????

Cats don’t have green blood vessels.

And it isn’t "really" necessary to have the flash a "foot or more" above the lens–2-3 inches for a good camera mounted flash that has the correct angle is sufficient to do the trick….

Mark
"The angle of reflection is equal to the angle of incidence." The reflecting surface in the eye is a very small target, accessed thru a very small ‘tunnel’.
The idea is to have the flash far enough removed from the lens so that the reflected light comes back an an angle that misses the lens. Is your flash far enough removed from the lens? Try a shot straight-on and see. Else: "Caveat raptor!"

Incidentally, I *hate* the red-eye preflash on cameras. "Alert, everybody! Here comes the picture! Everyone tense up!"

Good luck! . . . . patrick

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