I first read about the Zone System about 30 years ago, but never fully got into it because of marriage, children, etc., etc.. Well I'm back with the same enthu ziasm I had 30 years ago. I've got a new 4x5 camera and a couple of lenses and I am ready to go. I picked up a used copy of The Negative and read it from cove r to cover. I UNDERSTAND the Zone System. What I don't understand is the negat ive developement times associated with N-1, N+1, N+2 etc. Ansel's left brain re ally kicks in sometimes and I felt like I was back in my college physics and che mistry classes. Thats OK, but way more information than I need. Ansel wants you to do all the testing on this matter yourself. I don't want to. I find the sp ecs. from film mnaufacturers a bit confusing and also an unwillingness to commit to any of this by Kodak when I e-mailed them. They suggested I read The Negati ve. What part of the film specs should I be looking at, the contrast adjusting p art, or the push processing part ? The push processing part would seem appropri ate for N+1 and N+2, but wouldn't be much help for N-1 or 2. My best guess for m ost films is 1.5 times nomal dev for N+1 and 2 times for N+2. I'm not sure on N -1. Can anyone get me going in the right direction on this ? Thanks