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Caustics also appear within eyes when the direct sunlight travels diagonally through the cornea. Blog reader P.A. Farris sent me these photos she took of a black-crowned night heron. The caustic is an arc-like shape on the opposite side of the pupil from the highlight.
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If the light comes from far enough to the side, the caustic becomes a focused point.
Thanks, P. A. Farris
More on caustics in Color and Light: A Guide for the Realist Painter
Previously on GJ:
Caustics
Nephroid Caustics
Caustic Reflections
Wikipedia on caustic optics
2 comments:
Jim, Great stuff. I have painted this effect many times over without really taking the time to understand what really causes it- Thanks
Caustics are one of my favourite lighting effects, especially when applied to a juicy eye.
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