I have read Understanding Exposure by Bryan Peterson, a very good book, highly recommended I have now purchased another of his books, Exposure Solutions, but I read something I am now sure about so ask you guys if you can confirm for me please. [The books I purchase are Kindle ebooks, excellent and a fraction of the cost] First it talks about single-focal length lenses, they have Depth of Field Scale that makes it easy to preset focus for a given scene. So far so good. Then it says, most people go for wide angle lenses (I have), then he states that they don;t have the DoF scale, I agree. But he goes on the say they do however, have distance settings, which, similar to DoF scales, allow you to preset the DoF before taking the shot. Are these the mm focal distance measurement? He then continues and says... you'll find these numbers above the distance setting mark on the lens. He then says... set aperture to f/22 and then align a specific distance - 3 feet (1 meter) or 6 feet (2 meters) depending on the focal length you are using. Can someone explain this please? I am aware of the lenses mm settings but not sure how this relates to the 1 or 2 meters he is stating. Thanks in advance, I am very grateful. All questions are easy... if you know the answer.