What is Zone System?
This is developed by Ansel Adams. To make it simple, the whole process consists of these 3 major steps:
Choose the Exposure Index (EI) of a particular film using your photographic system by selecting the EI that produce the Zone I density at 0.1 above Dmin.
Select the exposure of the photograph by determining the Zone III area in the scene.
Develop the film so that the important highlight value to match the density of Zone VIII, i.e., 1.30 density above Dmin for diffuser enlarger.
B&W Developer Comparison
T-Max 100 (TMX 120) with D-76 (1:1)
T-Max 400 (TMY 120) with D-76 (1:1)
T-Max 100 (TMX 120) with T-Max Developer
T-Max 400 (TMY 120) with T-Max Developer