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Here is an article written by full time professional photographer, and owner of Balsman photography,  Kim Balsman.
The purpose of this article is to help us understand Ansel Adam’s famous zone system.

This article was posted here with the consentment of its writer.

Ansel Adams was a genius. He was methodical in his work and
extremely demanding in terms of the quality of his prints. Those who
admire his work or attempt to imitate his methods are often perplexed
or intimidated by the results. It seems that a vast majority of people
believe that Ansel Adams’ techniques, often shrouded in mystery, are
impossible to master. This is simply not so. This article is dedicated
to demystifying the clever, yet relatively simple Zone System so
masterfully devised by Ansel Adams and perfected by other virtuosos of
photography.

To fully understand and appreciate the Zone System, one must first
have at least a basic understanding of photography nomenclature.
Mastery of the Zone System requires significantly more dedication to
the fundamentals of photography and lots of practice. I will assume,
for the purposes of this article, that my readers have a basic command
of the principles of exposure - the interplay of light, shutter speed and aperture.

The f-stops here! The Zone System focuses on two very important
aspects of photography – image exposure and development, which
naturally centers on the f-stop (the size or opening of the aperture as
expressed by a number indicating the amount of light transmitted
through the lens). Unlike the vast colors, tones and brightness found
in nature, the Zone System recognizes the limitations of film and/or
digital image processors and works within these limitations. Sadly, no
single camera,
lens or film available today can absolutely equal nature’s immensity.
However, by utilizing the techniques of the Zone System we can
reproduce, as precisely as possible, images of nature that exemplify
its tonal ranges and varying degrees of brightness with little
discernable difference.

Imagine a ladder. The bottom rung of the ladder represents pure
black (Zone 0). The top rung of the ladder represents pure white (Zone
9). The mid-point of the ladder (Zone 5) represents 18% gray or the
accepted average reflectance of light from a given subject, which is
interpreted by your camera’s integrated light meter as the correct
exposure for both B&W and color images. From the mid-point, Zone 5,
each sequential step or zone represents a change of one f-stop. Zone 4
requires an exposure of one f-stop less than your meter reading (or
Zone 5). Conversely, Zone 6 requires an exposure of one f-stop more
than your meter reading. Therefore, the entire Zone System encompasses
a nine-stop differential, which is more than adequate to address even
the most daunting high contrast scene in nature.

Now, let’s add values to these Zones. These are values Ansel Adams himself associated with the nine Zones.

Zone 9 – known as key white or pure white – pure white paper or snow in bright sunlight.

Zone 8 – gray/white, near white – distinct highlight detail, like a white wall in sunlight or brilliant surfaces in flat light.

Zone 7 – light gray – pale “white” skin, a concrete walkway in sunlight.

Zone 6 – mid-tone gray – average “white” skin or shaded areas in snow on a bright, sunlit day.

Zone 5 – medium gray or 18% gray – darker “white” skin or lighter
“black skin,” light foliage or the dark blue of a clear blue sky.

Zone 4 – medium dark gray – slightly darker “black” skin, dark foliage or shadows in landscapes.

Zone 3 – very dark gray – distinct shadow texture is visible.

Zone 2 – dark gray/black – only subtle textures are visible.

Zone 1 – near black – shadows in faint light or rooms without light.

Zone 0 – key black or pure black – carbon or photo paper black.

Remember your camera is calibrated to read 18% gray as “correct” and
assumes that is the desired amount of light reflectance. Thus, it will
average the light readings of extreme shadows or highlights resulting
in over-exposed or under-exposed images, respectively. The Zone System
eliminates this problem by assigning these familiar “values” to each
zone. The key to success with the Zone System is to carefully
pre-visualize your subject and apply the correct Zone values to the
important exposure areas. Then, you must adjust your exposure settings
accordingly to accurately produce the results you want.

Let’s say you are on vacation and want to take a photo of
snow-covered Pikes Peak. It’s a typical sunny day in Colorado. You take
a meter reading of the snow, which suggests a shutter speed of 1/500
and a corresponding aperture of f/16. If you snap the photo using these
settings, the resulting image will be dull 18% gray. According to the
Zone System, snow in bright sunlight falls under Zone 9, which is four
stops above Zone 5, or 18% gray. Therefore, you must first open up four
stops to f/4 and shoot at 1/500. Now, your photo will clearly show the
brilliance of the white snow under the Colorado sun.

What should you do if you want to photograph an interesting rock
formation with a bright blue sky and fluffy white clouds in the
background? The rock formation is moderately shadowed with lots of
texture. You want to bring out as much detail in the rock formation as
possible. You take a meter reading of the shadowed areas of the rock,
which indicates a shutter speed of 1/60 with an aperture of f/2.8.
Then, you take a reading of the sky, which indicates the same shutter
speed but an aperture of f/16. Keep in mind that in high contrast
scenes, you MUST expose for the shadows if you want to reveal the
shadow details. Sometimes this means sacrificing some of the highlights
in your subject landscape. You decide that the shadowed areas fall
within Zone 2. Therefore, you must stop down three stops and shoot at
1/60 at f/8. Of course, this means that you will lose some of the
highlight detail from the bright sky. Don’t despair. All is not lost.

Recall that the Zone System integrates nine f-stops. Yet, the
latitude or exposure range of most readily available film varies from a
low of three f-stops to a high of seven f-stops. Likewise, photo paper,
in general, has a range of no more than five f-stops. How, then, can
you compensate for the limited latitude of film and photo paper? The
Zone System incorporates both exposure AND development techniques.
Ansel Adams used large format “sheet” film affording him more control
over the development of each individual negative. By varying
development time, plus or minus according to a comparative f-stop
scale, Ansel Adams was able to effectively defy the limited latitude of
his film and photo paper.

Contrary to the photographic rule of exposing for the shadows, you
should develop film for the highlights. Concentrating on the range of
brightness in a given image negative, Ansel Adams established the
following development scale:

Normal development time, plus 100% @ 3 stops

Normal development time, plus 50% @ 4 stops

Normal development time only @ 5 stops

Reduce normal development time by 20% @ 6 stops

Reduce normal development time by 40% @ 7 stops

The Zone System works best with large format “sheet” film since you
can isolate each section of the negative and vary its development time.
While you can apply these techniques to roll film, it would require
identical exposure for each frame, which isn’t very likely or
practical. If you are a digital photographer, like me, or a roll-film
photographer hoping to take advantage of all the aspects of the Zone
System, you can utilize both the burning in and dodging techniques.
Burning in refers to darkening specific areas of your image. Dodging
refers to lightening specific areas of your image. For digital
applications, you can use the tools in Adobe Photoshop. For film, you
can appropriately mark your prints for these advanced development
processes.

By employing both the exposure and development techniques of the
Zone System, you will be able to produce amazing images like those of
the masters. Ansel Adams was, indeed, an innovator. He created a unique
and valuable tool, in fact, a legacy for all photographers. Fine Art
Photography wouldn’t be the same without the Zone System.

I hope this article will help you to realize that the Zone System is
not complicated or mysterious at all. It merely requires a reasonable
investment in time, effort and careful but straightforward calculations
to achieve extraordinary results. If you wonder whether or not the
effort is worth it, simply look at a handful of Ansel Adam’s
photographs.

© Balsman Photography, LLC

This entry was posted on Wednesday, March 7th, 2007 at 10:52 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.