I totally agree, as will all on here I think, Bryan Peterson's 'Understanding Exposure' book or ebook is probably the best book anyone learning Photography could have, should have. Interestingly the book mentioned, which I am referring to in the post here is by, Bryan Peterson, I am wondering if maybe an older book based on the rep;lies so far. That said, I don't feel I should judge the book based on this one item, time will tell as I work my way through the book. I have today downloaded another App, called DOF easy, it has a rating of 5.0, very high. having downloaded it and checked it, along with explanations of every link, I can see why it is highly rated. There are areas in it I need to learn more about but it seems a very good App. Meanwhile my reading as been distracted as I am currently looking to improve my understanding of the Hyperfocal Distance Hyperfocal Distance Explained Thank you.