Colin.D wrote:

Not to forget that the original zone system strictly applies to
monochrome film. Very limited development variation can be applied to
color film without color shifts.


At least with ordinary Kodak consumer color film that's not true.
The contrast can be varied dramatically, especially in the "contrastier"
direction, without serious color shifts. Even before Photoshop I had no
trouble makng prints from such negatives. With Photoshop even the
worst color shifts I ever saw are completely correctable.

Doug McDonald