Don't use colored flash units!

Started Sep 5, 2011 | Discussions thread
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Barrie Davis
Forum ProPosts: 21,460
Re: Could be the glasses...
In reply to Kelowna, Sep 12, 2011

Kelowna wrote:

The problem could be with the eye glasses.

Earlier this year, one client I photographed had a yellow tint show in his glasses. I lighted the portrait primarily through a softbox which had not yellow tint at all. When I asked him if they were transitions (darken in sunlight) he said "yes".

Perhaps it is possible that the silver halide crystals in the glass, that darken in sunlight, are small enough when in low light to cause an interference pattern with the coating on the surface of the specatacles...... and the resulting frequency is between red and green in the spectrum, thus producing yellow.

Interference effects happen quite often in nature... and can produce extremely intense colours where no pigment is actually involved. The classic case is a thin film of oil on water making rainbows... also the colour of iridescent butterfly wings.

I'm just guessing here, but these kinds of things do happen.

Maybe you can test this suggestion with a polariser on the lens, to see if it makes a difference. I'm thinking the additional crystal matrix in the pola, --(linear type, maybe?)-- might de-colourise the reflection, even without rotation to subdue it... [???]

"Ahh... But the thing is, they were not just ORDINARY time travellers!"

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