Justin Case
Flashlight Enthusiast
- Joined
- Mar 19, 2008
- Messages
- 3,797
Eye shine for spotting critters:
I was taught this one by a field naturalist. Hold the light at the level of your eyes, and track the center of the beam as you scan a night scene. Because of the angle, you will catch "eye shine" reflections off the retinas of any critter with eyes (who happens to be looking at you, of course).
Eyeshine is also known as retroreflection. Same phenomenon as in street signs. In animals, it is reflected light off of the tapetum lucidum, not the retina. Otherwise, humans would also show eyeshine, but they don't because they don't have a tapetum lucidum.