This book is excellent. It's well written, explains the subject well and understandably, is well illustrated. The book covering both mechanical and computer filters, where and how they can be used. Where there might be alternative ways of achieving an effect the differences are covered and the author often says why he chooses one or the other. I knew a little about filters but this book has left me a lot wiser. I was particularly impressed with the way the author used a mixture of mechanical and computer again covering why. I will recommend this book to my fellow photographers, whether they are wanting to capture natural light and scenes, enhance that which they have already taken or create something different.