Ayash,
You understand that red-eye because you show the illumination of the red
blood vessels at the rear of the eyeball in your photo. You can do this at
any distance if your flash and lens are close enough. It is actually easier
to get/have red-eye with long lenses because the effective angle between the
flash and lens axis is smaller.
At 3 meters, the Vivitar flash mounted on your camera is perhaps 10 cm above
the lens axis. To the subject's eyes, this angle is small (.1 vs 3.0 or
arctan(1/30)), but still allows the flash to illuminate an inside part of the
eyeball below what you can see. The red spot is still there, but you can't
photograph it because it falls inside the eye and behind the 'white' of the
eyeball.
At 8 meters, the flash mounted on your camera is still 10 cm above the lens
axis, but now the angle is much smaller (.1 vs 8.0 or arctan(1/80)). To the
subject's eyes, your flash is shooting right down the barrel of your lens.
Now when you pop the flash, you can see the red-eye right thru the cornea or
lens of the subject's eye.
You have aligned things nearly perfectly to get red-eye.
Try a flash bracket, or if the Vivitar can tilt, bounce the light off of the
ceiling.
Regards, Bob S.
[EMAIL PROTECTED] writes:
<< Recently, I was taking some shots in a function (The organizers of the
function requested me to photograph the activities in the function). In
the question hour session, I was photographing a young boy who was asking
question. He was about 8 meters away from me and I was using PENTAX SMC
F 100-300mm f/4.5-5.6 at 250 mm focal length. He was not looking at the
camera and was unaware of being photographed. When I got back the
prints, I was surprised to see red eye effect on the eye of the
boy. The flash used was VIVITAR 2800 at red mode (if the subject to camera
distance (s) is, 6 m > s > 12 m, the flash should be operated at red mode,
according to the manual). I can not understand how this could happen at a
distance of 8 meters. Yes, it is true that operating at a focal length of
250 mm takes you near to the boy but red eye effect happens when the
subject is looking towards the lens and flash is fired from a close
distance say about 3 - 4 m. May be a flash bracket can help me to get rid
of the problem.
Any comments/explaination is appreciated. >>
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