BTZS refers to “Beyond The Zone System,” the title of a book written by Phil Davis and is now in its 4th edition.
BTZS is “beyond” the Zone System in several ways. First, we test our materials using sensitometric methods to produce test data that are more comprehensive and more reliable than conventional empirical methods can achieve. Second, we use sophisticated computer programs to analyze the test data in the lab, and generate working data in the field. Third, we replace “N-numbers” as indicators of development extent with Average Gradient values which are more specific and more reliable. Finally, we recognize that both science and art are essential elements in photography. BTZS can equip you with the knowledge and skill you’ll need to handle your materials effectively, but that’s as far as it can go; it’s up to the artist in you to apply what you’ve learned to produce images that are worth looking at.