I bought this as an update to the old Kodak Master Photoguide, which was smaller and is now out of date only because the films have changed.This books is an excellent reference for photographers. It should be in your field kit. It contains a number of essential reference tools, ranging from a description of current Kodak films, to aides for estimating exposure, reciprocity correction, and proper filtration.The topics are not exhaustive, as one would expect from a textbook. But then, this isn't a text, it's a field handbook. As such, it fills a need very well.