Red-Eye - wuz - RE: [thechat] Re: High End Filters for Digital Cameras -- Found

Luther, Ron Ron.Luther at hp.com
Wed Oct 9 11:33:16 CDT 2002


Hi Javier,

Exactly so!

In portrait flash photography, (taking a picture of a person
while using your flash), a "straight ahead" flash will often
reflect back off the subject's retinas and cause their eyes to
appear to be red in the developed image.

[My understanding is that this is because the retina is ... well,
it's red.]

While there are a couple of ways to get around this:

- Use a diffuser to 'soften' the light so it doesn't reflect back
as strongly.

- "Bounce" the flash off a nearby object like a wall, ceiling, or
a shiny car so that it enters the subject's eye at an angle and
doesn't reflect directly back at the camera.

- Attach a cable to your flash to get it off the camera and aim
it at the subject from an angle that doesn't reflect back into
the lens. [Above the subject and aimed down from the 3/4 side is,
if I remember correctly, called "Rembrandt" lighting - and is very
popular in portrait work.]

.... but *all* of these techniques rely on changing the angle of
the light on the subject so it doesn't reflect straight back into
the camera.

Now ... on a point-and-shoot camera, (or most digital cameras),
that itty bitty built-in flash is very very very close to the lens.
The light it puts out pretty much goes straight at the subject and
bounces straight back at the camera ... very small angle.  This is
going to give you a lot of pictures with red eye.

That "red eye reduction" feature these cameras have is a circuit that
causes the camera's flash to fire several times quickly in succession
at partial power - before - firing once again (at proper strength) to
take the picture.  The idea is to try to dilate the subject's pupils
so that very little light will reflect back from their retinas ...
thereby reducing 'red eye'.  [1]

So it didn't really "fail" --- it just can't be 100% effective because
you still have that very very very narrow angle between the flash
and the subject.  The ONLY way to make red eye go away completely
is to change the angle that the flash hits the subject ... or, of
course, get really really good at post-processing techniques!  ;-)

... which brings me back to asking if anyone's found an 'inexpensive'
way to change the flash angle. [I know how to do it the 'right way' -
and it costs money!]

Dang!  It almost sounds like I know what I'm talking about!   ;-)


RonL.

[1] It also means your subjects have to keep fairly still. Which
doesn't work real well when you're shooting some 18 month old
grandkids!  ;-)


-----Original Message-----
From: javier velasco [mailto:lists at mantruc.com]

do you mean the red eye reduction feature? (i don't wee the relation
between that and an external flash unit)

if it's that, i haven't used it much, but it has failed (i have gotten
some red eyes in pictures that were shot with the feature on)



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