How the Zone System works
Place each scene brightness on a numbered zone scale from 0 (black) to X (white).
Where to find it
Tools tab Zone System
Summary
Interactive Zone System calculator: drop spot readings on the live preview, see which zone each lands on, and pick where you want each spot to fall.
Detail
How it works
The Zone System, developed by Ansel Adams, is a way of placing each meaningful brightness in your scene onto a numbered scale from Zone 0 (pure black) to Zone X (pure white). It lets you decide ahead of time which areas will print as detail, which will go to black, and which will blow out.
The zones
Zone 0 is paper black, no detail. Zone V is middle grey (the meter's default reference). Zone X is paper white, no detail. Zones I and II hold faint detail in deep shadow. Zones VIII and IX hold faint detail in bright highlights. Zones III through VII are where most of the picture lives.
How to use it here
Drop a few spot readings on the live preview. Each spot becomes a row in this modal showing which zone it lands in. You then decide where you want each spot to fall and the meter tells you how much to compensate.
Place a shadow, let highlights fall
The classic black and white technique. Pick the darkest area you want detail in, place it on Zone III. The meter shifts exposure so that area gets enough light. Highlights then land wherever they land, and you adjust contrast in development.
Place a highlight (slide film)
For slide film and digital, do the opposite. Pick the brightest area you want detail in and place it on Zone VIII. Shadows then fall where they fall.
Clipping warnings
Spots that would land below Zone 0 or above Zone X are flagged because they will lose all detail. That is your cue to either pick a different exposure or accept the loss.