Using a high contrast scene and knowledge of Ansel Adam’s Zone System produce photographs rendering as much detail in the brightest and darkest areas of the photograph.
Ansel Adam’s Zone System
In his seminal book, The Negative, Ansel Adams (with the collaboration of Robert Baker) painstakingly describes the Zone System as enabling the photographer to ‘relate various luminances of a subject with the grey values from black to white’ (1). The diagram below visually and verbally describes the eleven zones which Adams chose to designate by the Roman numerals 0 to IX.
Adams goes on to describe three basic subject contrast scenarios; the normal subject range, the short-scale (or low contrast) subject and the long-scale (high contrast) subject. Taken from the book examples of these scenarios are as follows:
The normal subject range
By placing the darkest area requiring detail in Zone III and therefore as a result, in this example, placing the lightest area requiring detail within Zone VII, a ‘full-range’ negative is produced.
The short-scale subject
This flat, low-contrast image uses less than the full exposure scale.
The long-scale subject
By placing the darkest area requiring detail in Zone III causes the lightest area to fall within Zone IX – which with normal development will print with no detail. An image of this sort leaves the photographer with no latitude to increase exposure (to lighten the dark areas) without turning the light areas pure white.
So what can be done?
In film photography, it is often said ‘expose for the shadows, develop for the highlights’. What does this mean in the context of a long-scale, high contrast scene? In The Negative, Ansel Adams describes a development technique called Contraction (or N-1, N-2 etc). In basic terms, this means that the negative is overexposed during shooting and subsequently underdeveloped. The contraction process has a relatively small effect on the darker areas of the scene and conversely a greater effect on the lighter areas. The effects of Contraction can be visualised in the following diagram.
An N-1 Contraction development to solve the brief
Normal development – Using Ilford HP5+ 4×5 film I selected a high contrast scene of a white-leaved plant in bright sun. I metered (using a Sekonic in reflective mode) for the darkest part of the scene that I wanted to show any detail – it showed 1/15 second. I then metered for the brightest part of the image – 1/400 second. That’s a five-stop difference. So to place the darkest area into Zone III would require a two-stop reduction ie shoot at 1/60 second. This would place the brightest area into Zone VIII. See the image below left. I then normally developed this first exposure.
N-1 Development – Using the same meter settings I made the second exposure at 1/30 second. This would result in the dark areas being in Zone IV and the lightest overexposed in Zone IX. But with the N-1 development Zone IV stays within Zone IV whilst Zone IX becomes Zone VIII. See the image below right.
The effect can be clearly seen on the respective histograms.
Conclusion and final images
Using Ansel Adams Zone System to evaluate a high contrast scene and then increasing exposure and reducing development satisfies the brief, namely to produce photographs rendering as much detail in the brightest and darkest areas of the photograph.
The two final images are shown below.
(1) Adams, A., 1981. The Negative. 2nd ed. New York: Little, Brown, pp.47-97.