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Old Feb 7, 2006, 9:25 PM   #1
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How much does the distance between a camara's lens and its flash affect redeye? The reason I ask is that I have a newer camera (canon s50) with horrid redeye and an older camera (canon A10) with much less. The only reason for a difference I can see is that the new one's flash is much closer to the lens.

Generally I'm not happy with the s50 and am considering ditching it for another model. If flash/lens seperation matters for redeye it may factor in on my next choice.
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Old Feb 8, 2006, 8:03 AM   #2
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Yup, that's the key thing. If the angle from the flash to the eye back to the lens is small enough, you can see the back of the retina become illuminated by the flash -- you get red eye. The "red eye reduction" system tries to tease the pupil to close down a bit, lessening the size of an angle that can reflect flash off the back of the eye into the lens. But your best bet is to get people to look a bit away fom the camera when you're shooting photos with flash using a built-in flash. You''ll often see photographers hold their hand out to their side and tell people to look at the hand. This is the "manual" form of red-eye reduction


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Old Feb 8, 2006, 2:31 PM   #3
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Just to add to tclune:

Distance is indeed the key, but on a digicam there is really only so far away from the lens you can put the flash. You will see some improvement and indeed some cameras have a better reduction method (pre-flash flicker that causes pupils to dialate) but you'll still have red-eye to some extent. It's one main reason why you see pro wedding photographers use a flash bracket on their camera - to really create distance. That's not an option on a digicam, so you're stuck picking a model that does a little better job than what you have. Just be prepared for the need to still remove it in post processing. Almost any software package will have some type of redeye removal.


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Old Feb 8, 2006, 3:10 PM   #4
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Quote:
pre-flash flicker that causes pupils to dialate
just a quick point. Dialate should read constrict
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Old Feb 8, 2006, 3:18 PM   #5
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Old Feb 8, 2006, 3:20 PM   #6
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Just a question: Can a message be deleted from this board?


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Old Feb 8, 2006, 7:28 PM   #7
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Yup, having to small a lens-eye-flash angle will get red-eye. That means either moving the flash away from the lens, or moving the camera closer to the subject. Using the short endof your zoom and moving closer will reduce red-eye.

Given the perspective "distortion" that comes from moving close,moving closeis not a good technique for shooting someone who is sensitive about having a big nose.
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Old Feb 9, 2006, 5:23 AM   #8
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BillDrew wrote:
Quote:
Yup, having to small a lens-eye-flash angle will get red-eye.¬* That means either moving the flash away from the lens, or moving the camera closer to the subject.¬*¬* Using the short end¬*of your zoom and moving closer will reduce red-eye.

Given the perspective "distortion" that comes from moving close,¬*moving close¬*is not a good technique for shooting someone who is sensitive about having a big nose.
But with compacts you would have to push camera directly front of face to get angle big enough for not getting red eye.

And that's the reason why these "red eye reduction" modes of ulteacompacts are bad jokes/insult. Flash is just so close to lens that pupil would have to close completely.



PS. tclune, apprently not, but you can add that question to existing message instead of writing post only for it.
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Old Feb 9, 2006, 7:39 PM   #9
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Thanks for the replies and additional tips.
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