Re:lighting and angles
David Webb mentioned complete internal reflection as a possible concern,
when considering the angle the light enters the water from. The phenomena
he mentioned only occurs when light travels from a media with a higher
index of refraction to a media with a lower index, eg water to air. When
you are swimming underwater, you can see straight up out of the water, and
roughly 50 degrees to either side of vertical.Beyond that, the water
surface will look like a highly reflective mirror. In our favor, going
from air to water, the light will tend to bend back toward the light. We
do get some benefit from total internal reflection when the light goes
through the glass into air.
David may have been referring to total polarization, which occurs when you
look at the surface of the water and get a nice bright glare at a certain
angle. This angle is known as brewster's angle, and all the light at that
angle is polarized strongly, and hence creates a glare. A good pair of
raybans will eliminate it.
Physics makes the world go round.