Although published in 1954 this is not a very difficult book to find for purchase online. Organized by H.J.Walls and edited by Focal Press is one of the few books written for amateurs that goes beyond the surface of the principles of optics, the nature of light, sensitometry and the characteristics of lenses and photographic equipment. A great source for those who want to understand the technique of photography where it lends the knowledge of physics and chemistry.