Pre-flash and red eye

S

steveb

Suspended / Banned
Messages
786
Name
Steve
Edit My Images
No
Very rarely when permissible I have no option but to use on camera flash. Last night was such an occasion, available light was not sufficient and flash couldn't be bounced. I shot with on camera flash, using pre-flash. When editing I noticed the pupils of all but one were smaller, and had no red eye. In every shot one person still had enlarged pupils and they were a dull red. Easy to edit out, but I'm curious why. Has anyone ever come across this before and do they know why?
 
Last edited:
A valid point, but most certainly not the person effected.
 
Contrary to marketing claims, a pre-flash isn’t that useful as a red eye reduction tool.
It’s physics. And I know you made your decision, but the circumstances that create red eye are the ones I’d do anything to avoid
 
The "Red" in red eye is the blood soaked mess at the back of the inside of your eye being reflected. The pupil of your eye (the black bit) isn't black at all, it's a hole where the light gets in.
The pre-flash makes the whole smaller. So at best "Anti red eye" flash gives you a smaller red eye to edit out.
 
Shame I was in a church hall with a very high brown wooden roof, so no bounce flash possible. Just incase I ever need on camera flash again I'll turn off pre-flash, don't like the delay it introduces. Still a mystery why I only had problems with one of 5 people.
 
was the one of the five shot within a group shot or as an individual ?

maybe if it was a group shot they were just enough of an angle for the light not to reflect directly back into the lens

iv'e seen it before in group shots but have no real explanation why apart from the stab in the dark above
 
It’s simple physics, it’s about the size of the pupil and the angle.
 
The speed with which the pupil responds to changes in light varies between individuals, usually increases with age, and its size and speed of reaction is also affected by some commonly prescribed drugs, as well as some common recreational drugs. How much red eye effect is produced varies also with the distance of the camera flash above the lens. That's why a big camera mounted forward pointing flashgun will produce less red eye than a pop up flash (higher above the lens), and why using the camera mounted flash pointing up to bounce off a flash card, such as a piece of white A4 paper attached to the flash with a rubber band, will produce even less red eye, as well as a slightly softer light.
 
Could always get yourself a flash bender with diffusion panel. You might not want to take the flash off the camera!

‘Might’ ;)
 
Simples really ,there zombies
 
You must log in or register to reply here.
Back
Top