The effective range of tones that can be reproduced based on the doubling or halving of exposure values with digital photography does not have as wide a spectrum as film. Film can produce a wider range of values (tones).

There is a rich history to the Zone System which was popularized by Sir Ansel Adams. This majestic artist and technician was very influential as an educator for photographers. His images of Yosemite and other national treasures are recognized by many. The marketing of his work in the form of quality books and posters (almost always printed as duotones) has been spectacular. Currently, Googling "Ansel Adams" will yield about 7,000,000 results proving that he certainly is (still) spoken of by many.

To prove his influence, Google "the Zone System" and you'll find over 43,000,000 results. Certainly many have decided to reference the Zone System on their websites. Many have written books on the topic. I'll suggest that the various interpretations of the Zone System almost qualify for it being a religion. A bold statement but one that, none the less, could strike controversy when it comes to discussing how we might put it to use in today's digital world of photography and videography.