I eluded to the "Zone System" in my last blog. The Zone System was developed by Ansel Adams and Fred Archer as a simple and straightforward method by which they could control exposure.
Please note I am going to first talk about the Zone System from a photographic paper perspective and using B&W imagery. Later I will show how this can be used in all media types.
So what is this system and why did it come about. It came about because we see the world in a range of tones and brightness and darkness, and the humble light meter sees it as a uniform grey often refered to as 18% Grey. So to state the obvious it has something to do with exposure and the placing of them into zones. But what are these zones? A zone is the print value (tone) that will be produced when the image is properly exposed and developed for that zone . YOU determine the exposure, the exposure determines the Zone you get.
So how many zones are there? The Zone System assigns numbers from 0 through 10 to different brightness values, with 0 representing black, 5 middle gray, and 10 pure white; these values are known as zones. To make zones easily distinguishable from other quantities, Adams and Archer used Roman rather than Arabic numerals. So the mid tone 5 is known as Zone V. Each zone zone differs by a factor of two (2) so there is a one stop differance between each zone.
Since there are 11 zones, how many are actually use full to the photographer? The usefull ones are Zone I through Zone IX. These are the Zone I near black, with slight tonality but no texture and Zone IX slight tone without texture; i.e. glaring snow.
Zone 0 – the darkest possible black on the print
Zone I – the first tone above complete black
Zone II – the first signs of texture, slight detail
Zone III – dark areas with significant texture
Zone IV – dark foliage, etc in open shadow
Zone V – middle gray
Zone VI – Caucasian skin in sunlight
Zone VII – full textured highlights
Zone VIII – slight texture highlights
Zone IX – first tone darker than pure white on the print
Zone X – the brightest possible white on the print
Zones I – IX are considered the dynamic range (tones that will separate and have distinct tonalities between complete black and white)
Zones II – VIII are considered the textured range (tones that will show some or complete texture of the object)
It is worth noting, the number of zones you have available to you to use is dependant on the contrast ratio the print medium can handle. Photographic paper can do 100:1, dependant on quality of paper and type of processing. A computer printer’s tonal output depends on the number of inks used and the paper on which it is printed. So a good print is about 100:1. I know when you look at the image in print the tones are smooth and so it is difficult to see these ratios.