Light: Science and Magic: An Introduction to Photographic Lighting
Fil Hunter, Steven Biver, Paul Fuqua
$26.47
This is not a lighting cookbook. Instead the authors discuss the fundamentals of physics of light and optics, and then apply that knowledge to a variety of typical and commercial photographic problems. Gear tips and tricks abound, but in the context of the principles of lighting choices. Buy this at the same time you buy your first flash.