Don't forget that many of us here at APUG have experience in macro work in multiple format sizes that may not be covered in many of the books including those by Heather Angel and John Shaw. I have several books on the subject including those mentioned as well as those in the Kodak series. We can share our knowledge and experience. I think that it may be quite valuable particularly for the beginner. Even for those of us that only do it occasionally will find it beneficial for instance when requiring bellows factors for LF and for those using cameras without inboard meters.