BetterPhoto Q&A
Category: New Questions

Photography Question 
Kathy Moran
 

White Pupil


 
 
I took a picture of my niece using a flash(others around me were taking her picture at the same time. The picture had one white pupil and one red pupil. What causes this?


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8/24/2007 2:17:12 PM

 
Alan N. Marcus   Hi Kathy,

The structure of the eye is a sphere. Light that enters the eye sphere transverses the lens plus fluids and baths the light sensitive membrane at the back of the eye (retina). Since the retina and surrounding tissue is translucent and nourished with a rich blood supply, should light be reflected backwards, it will exit the eye tinged bright red. Bright light will generally enter and exits via reflection. The path of the reflected light is highly directional. For the most part, the return path retraces the entry path. Thus reflected red light is mainly directed back at the originating light source. You see this all the time driving at night. An animal caught in the headlight glare seems to have glowing eyes (nighttime animals don’t necessarily reflect red light their retina is pigmented yellow-green for better night vision). The animal headlight thing is enhanced because when in a car you are seated over or near one of the headlights. This is known as on-axis (position). Road signs use this principle. The sign paint is weighed down with glass beads that reflect back co-axial light.

The camera with a self-contained flash has little separation between flash and lens. This structure is also known as on-axis. This is also true of clip-on flash units; these are normally also mounted too close to the lens thus perform as an on-axis devices. The cure red eye the flash is dismount so the flash and camera can be separated by 20-30 inches or more. Why one red eye? Likely the angle of view of the outside eye was far enough off-axis to avoid red eye it was dilated and the other not. Dilated eyes are more likely to display red eye. Some cameras pre-flash to cause the subjects eye to contract to a tiny diameter. This greatly reduces red eye.

Alan Marcus (dispenses marginal technical advice)
ammarcus@earthlink.net


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8/24/2007 3:23:57 PM

 
Bob Cammarata
BetterPhoto Member Since: 7/17/2003
  Kathy,
I don't want to sound like an alarmist but only one red pupil and one white may be a sign of a serious medical condition.

I heard of a similar situation on talk radio one morning and the "call-in doc" recommended an immediate visit to an eye doctor.
I found this information by doing a quick search on Google.

It may have been just the angle of the flash but it probably wouldn't hurt to e-mail the photo to your doctor just in case.

Bob


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8/24/2007 11:38:30 PM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
  Kathy,
In short what you are seeing are "catch lights".
There can be a catch light for each light used.
But they should be there ta add life to your subject and are caused by your light source.
I hope this helps,
Debby


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8/25/2007 7:10:14 AM

 
Alan N. Marcus   Catch lights are generally white glare spots generated by reflection. Catch lights are generated at the outer surface of the eye due to the smooth texture of the tissue and the presences of moisture. The surface of the eye thus glistens and sparkles as it reflects light. Catch lights are considered a desirable feature in portraiture as they impart impressions of life and health. Classic portraiture is highly influenced by the oil painting artist of the past. The generally accepted wisdom is one catch light per eye at about the 2 or 10 O’clock position. This gives an illusion of only one light source occurring about midday. Often to enhance an illusion or mood such as window lighting or the like, rectangular catch lights or multiple catch lights are also desirable. No rules or laws just tradition.

Red eye is not a catch light. Red eye is light that entered the eye, transversed to the retina, picks up a reddish tinge due to the copious blood supply, reflects backwards and retraces the entrance path. Almost always, the origin of catch lights is the close proximity of the illuminate to camera lens.

Alan Marcus (known to dispense debatable techno babble)
ammarcus@earthlink.net


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8/25/2007 2:43:04 PM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
  Catch lights can and will show in the pupils as well, depending on how large the light source and one to two depending on your light set up .
The only other reason pupils turn a grey( to blue grey) white is due to deterioration of the pupil.
Seen in animals when cataracts are present.
I hope this helps,
Debby


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8/26/2007 9:46:02 AM

 
Mark Feldstein
BetterPhoto Member Since: 3/17/2005
  Bob makes an extremely excellent point Kathy, and for a number of reasons: First, we can't see the photos you're talking about since they didn't upload. Second, since there were multiple flash units you don't know what kind of reflection you were seeing.

Personally, in years of portrait shooting, I've never seen a catchlight in a pupil since when the pupils are that dialated (open) they expose the rich blood supply of the rear of the occular chamber and the retina, which is what Alan was talking about. The iris, toward the front of the eye, is where the reflection comes from. According to the link Bob posted, white pupils, (white reflections off the pupil) are a sign of eye disease. Although as it notes, in some very dark eyed kids, you may not visualize the retina in some flash photography.

Third, and most importantly, since overall health is often reflected in how the eyes appear on examination, an eye exam for a kid even as part of a routine physical, is an inexpensive, non-invasive procedure that helps ensure their general health and the health of their eyes.
Take it light :>)
Mark


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8/26/2007 10:34:29 AM

 
Kathy Moran   Thank you for your help. I really appreciate all of your feedback. My sister did take my niece in for an eye exam to make sure all is well...and it is.


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8/29/2007 9:20:36 PM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
 
 
  Catch lights
Catch lights
© Debby A. Tabb
Nikon D200 Digital...
 
 
Good morning,
I deal with this all the time.
and explain it daily.


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8/30/2007 6:05:15 AM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
 
 
  Catch Lights 2
Catch Lights 2
This will be great to add to my portrait Cds, Thanks fo the ideas.
© Debby A. Tabb
Nikon D200 Digital...
 
 
Sorry, I missed the other one.


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8/30/2007 6:16:42 AM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
 
 
  Catch lights in a healthy animal
Catch lights in a healthy animal
I have to get on the road here, but I will see if I can come up with a unhealthy animals eyes.
I know I have some.

© Debby A. Tabb
Nikon D200 Digital...
 
 
In Animals.
Being that I teach Photographers for a high paced company right now,I shoot more then most photographers shoot in a few months.
While teaching in LA right now we shot :
Aug.33+29+31+32(so far this week,and we close the week saterday)=125 so far this month, and that does not include what I shoot from my home studio on off days.
I Love doing this job of teaching others and I hope this helps.
Thank you, it has been useful to me as well, giving me another teaching tool.
Thanks again,
Debby


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8/30/2007 6:39:43 AM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
 
 
  Close up Pupil
Close up Pupil
© Debby A. Tabb
Nikon D200 Digital...
 
  Human close up pupil
Human close up pupil
© Debby A. Tabb
Fuji FinePix S2 Pr...
 
 
This is a quote off the web site Bob listed...
....Can a white dot picture be nothing?
Yes, sometimes we photograph the optic nerve and it will reflect exactly like an eye disease. With children from birth to five years of age we want to rule out retinoblastoma immediately and pray that it is nothing. Always follow up if you get a strange photo.


I wanted to post this as I was following up with my research so I have all my info correct as I begin to add this info to my training.


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8/30/2007 7:28:25 AM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
  Moving This thread for Rod.
Thank you for your email,this thread had examples.
Have a great day!


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9/10/2007 6:25:07 AM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
  good evening Rod,
don't lose it this time,lol,lol.
I had a heck of a time finding it.
Have a great evening,
Debby


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9/16/2007 10:16:04 PM

 
Debby A. Tabb
BetterPhoto Member Since: 9/4/2004
 
 
  Unhealthy Canine Eye
Unhealthy Canine Eye
© Debby A. Tabb
Nikon D200 Digital...
 
 
and Rod since you asked ,
here is that unhealthy eye.


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9/16/2007 10:31:27 PM

 
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