Zone System and L values
Zone System is defined in terms of 11 zones. In practice I process my photos in Darktable and work with lightness values ranged from 0 to 100. Knowing correspondence between Lightness values and zones is useful, because it gives a good starting point when I decide how light or dark the subject should be.
This is the zone scale translated into lightness values:
|I||9–18||Near black, with slight tonality but no texture|
|II||18–27||☑||Textured black; the darkest part of the image in which slight detail is recorded|
|III||27–36||☑||Average dark materials and low values showing adequate texture|
|IV||36–45||☑||Average dark foliage, dark stone, or landscape shadows|
|V||45–55||☑||Middle gray: clear north sky; dark skin, average weathered wood|
|VI||55–64||☑||Average Caucasian skin; light stone; shadows on snow in sunlit landscapes|
|VII||64–73||☑||Very light skin; shadows in snow with acute side lighting|
|VIII||73–82||☑||Lightest tone with texture: textured snow|
|IX||82-91||Slight tone without texture; glaring snow|
|X||91–100||Pure white: light sources and specular reflections|
Hence, “dynamic range” is L=[9,91] and “texture range” is L=[18,82].