Snell's window
From Wikipedia, the free encyclopedia
Snell's window is a phenomenon by which an underwater viewer sees everything above the surface through a cone of light of width of about 96 degrees.[1] This phenomenon is caused by refraction of light entering water, and is governed by Snell's Law.[2] The area outside Snell's window will either be completely dark or will show a reflection of under-water objects.
Underwater photographers sometimes compose photographs from below such that their subjects fall inside Snell's window, which backlights and focuses attention on the subjects.
Snell's window is also called 'Snell's circle'[3] or 'optical man-hole'.[4]
[edit] References
- ^ Martin Edge and Ian Turner (1999). The Underwater Photographer. Focal Press. ISBN 0240515811.
- ^ Robert Williams Wood (1914). Physical Optics. The Macmillan Company.
- ^ Dave Hughes (1990). Tactics for Trout. Stackpole Books. ISBN 0811724034.
- ^ David K. Lynch and William Livingstone (2001). Color and Light in Nature. Cambridge University Press, 79. ISBN 0521775043.
