Discusses the optics of fly fishing, considering where to cast the fly once a fish is seen. Also considers what the fisherman looks like to the fish, examining refraction at a water surface, actual and apparent light rays, and how sticks in the water might look to a fish. (JN)

Suggests a method treating geometric optics using a microcomputer to do the calculations of image formation. Calculations are based on the connection between the composition of lenses and the mathematics of fractional linear equations. Logic of the analysis and an example problem are included. (JM)