Two books are almost essential reading:

"The Hot Shoe Diaries" by Joe McNally. Many will be put off perhaps by the fact that Joe uses Nikon gear, but they are going to miss some real treasures. Get over that and learn from a real master - then learn how to translate his concepts into what you can do just as well with Canon gear.

"Speedliter's Handbook" by Syl Arena. This is a superb book. Syl is doing his best to communicate all he knows and show you how to make excellent pictures.

The Speedliter's Handbook is one of those rare books where you feel like a real expert is taking you under his wing and trying to show you all he knows. The same is true of Joe McNally's book - he is not holding back and is eager to pass along what he has learned.

Also essential reading is the "strobist" website online. Here we have another master of off camera flash eager to teach people everything he knows. This has become the online center for information regarding photography using portable flash equipment.

• Strobist website

I will mention, with reservations, the book "Mastering Canon EOS Flash Photography" by NK Guy. This is a good reference book for historical information and Canon flash esoterica, but not a book that will serve you well if you are looking for a book to teach you how to use your gear to take pictures.