If you work with photography for very long, you will hear about a technique for determining optimal film exposure and development called the Zone System. It was developed in 1941 by Ansel Adams and Fred Archer. It provides a systematic method of precisely defining the way you visualize a subject and the final results that are obtained. It originated with Black and White Sheet film, but it has evolved to both Black and White roll film, color film, both negative and reversal as well as digital photography.
Over the years, the Zone System has gained a reputation of being impractical and hard to learn. Chris Johnson, in his book The Practical Zone System says that this is wrong. If approached in the proper way, the Zone System can be very easy to learn. Chris Johnson studied photography with Ansel Adams, Imogen Cunningham and Wynn Bullock and is a Professor of Photography at the California College of the Arts.
The Practical Zone System breaks down into 10 chapters and 21 appendixes covering 284 pages. The authors goal, as was in the prior three editions, is to teach you the Zone System without going into all of the science behind it. He plans to teach you the principles and the logic, and how it applies to real life.
"Chapter 1, "Will it Come Out?" begins by explaining what the Zone System is by using a series of questions and answers to explain the system, explain why photographic technique is so important and to dispel some myths about the Zone System.
Chapter 2, "Print Quality and Negative Contrast", explores subject contrasts and how they are affected by the types of photographic papers that are being used. Here the definition of contrast is defined, as are the concepts of overexposure, underexposure, overdevelopment and underdevelopment.
Chapter 3, "The Control of Negative Contrast", explains the rule of "Expose for the shadows and develop for the highlights". Here you learn the techniques of Normal-Plus and Normal-Minus development.
Chapter 4, "The Zone", gets into what the Zone System really is. It is a visual ruler that allows photographers to measure between normal, low and high contrast subjects. It is explained by using a Zone Ruler. It explains the black zones, white zones as well as the textured zones.
Chapter 5, "Exposure", begins by explaining the light-meter and how the can be used to measure the light on a subject. It explains the problems with finding the correct exposure and the concept of previsualization; the act of determining what you want the final print to look like.
Chapter 6, "Development", shows that once you have set your shadow area on Zone III, you now have to consider the effects it has on the other values of the scene that you are photographing. Here you must now figure your highlight area, and how does this affect development.