Pre Visualisation is certainly one of those buzz words we see appearing in lot's of books related to fine art photography. I am steadily wading through The Negative book for the fourth time and starting to pay more attention to what Ansel is talking about. There are many areas in the book where he talks about visualisation especially at the point of capture where he places important low values on a particular zone be it 3, 4 or in some cases 5. From this initial placement, he can quickly determine where the remaining zones fall. For your own work, how often do you practice the pre visualisation method and pay close attention to where all the zones in the image will fall after determining your base shadow zone.