As I began my learning experiences in flash photography, I came across a very interesting and useful web site, PhotoNotes, by NK Guy. Because I use Canon equipment, I was especially pleased to find that a comprehensive section on Canon cameras and flashes was part of the site. This section reads like a book so I was not surprised when NK Guy's book, "Mastering Canon EOS Flash Photography" was published this year. I knew that this would be a good book; the only question was "Why buy it?". Surely the book would be the same material that I was reading for free on his web site. Well, it is and it isn't. In the end, I actually bought the book for convenience and as salve for my conscience.
I'm glad I bought the book. This 419 page book is by far the most comprehensive book that I have on flash in general and Canon flashes in particular. In his book, NK Guy expands greatly on the information in his web site and illustrates it profusely. Virtually every page in the book includes at least one photograph or illustration and usually more than one. Plus, it's a good read -- just finished it.
Although "Canon" is included in the title, the book also includes a chapter on studio flash, a chapter on flash accessories including various light modifiers, various flash triggers and even third party small flash units. Of course, the Canon products are described and explained in the most detail. More than an equipment book, NK Guy also included chapters on basic and advanced flash and lighting techniques.
This is a good book and especially so if you use Canon equipment.
(I bought my own copy and have no affiliation whatsoever with NK Guy -- just liked the book and thought you might like it too.)