The Zone system was formulated by Ansel Adams and Fred Archer as a way of determining exposure.  The tonal scale is divided into eleven segments as shown below.  given that in photography we do not want pure black or pure white (under- and over-exposure), for practical purposes there are nine zones.

Whilst I don’t specifically follow the Zone System, I do follow its principles instinctively, viewing a scene and adjusting exposure in camera depending on the overall tone.

In the image below I was conscious of maintaining exposure in both the rocks and sky.  To maintain a dynamic range within my camera’s capabilities I used the rock to shield the sun and kept the exposure as dark as I could without underexposing the rock.

In the below image of a beach on a sunny day I had to prevent the people from becoming silhouettes whilst being careful not to overexpose the sky.

In the portrait image below I kept some definition in the shadows whilst ensuring the girl’s white top did not overexpose.  On the high resolution version of this image, enough detail is kept in the shadows to see a cobweb in the window.

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