The Digital Zone System

If you thought DSLRs and new technology made the Zone System obsolete, think again. Updating the classic Ansel Adams tool for proper exposure will make your digital photographs as good as they can be.

Michael Frye

When Ansel Adams developed the Zone System with Fred Archer in 1940, he gave photographers a tool great for controlling their images—but only with black-and-white film, and only with view cameras, where sheets of film could be processed individually. Today, any photographer with a digital camera can have even more control, whether working with black-and-white or color.

Zone System Basics
Zone 5 represents a midtone in the scene. Anything one stop darker will render as Zone 4, two stops darker, Zone 3, and so on. Anything one stop lighter will render as Zone 6, two stops lighter, Zone 7, etc. Most digital cameras can hold detail in Zones 3 and 7, but not beyond. In other words, Zone 8 and above are washed out, and Zone 2 and below are black. A light color will lose saturation above Zone 6, and a dark color can’t go below Zone 4 without becoming muddy.

Zone 0
Pure black

Zone 1
Nearly black

Zone 2
A hint of detail

Zone 3
Dark, with good detail but muddy color

Zone 4
Dark tone or color

Zone 5
Middle tone,
medium color

Zone 6
Light tone or pastel color

Zone 7
Light, with texture but faded color

Zone 8
A hint of detail, but essentially washed out
Zone 9
Nearly white


Zone 10
Paper white

Such unprecedented power creates wonderful opportunities, but also can lead to confusion. How do you apply these controls? How far should you go? Do you have to reinvent the whole photographic process? No—because while the tools may be different, the basic principles of the Zone System still apply. The Zone System gives us a vital framework for understanding and controlling contrast in our images and a path to making prints with a full, rich range of tones—the range of tones for which Adams’ photographs are so famous.


This Article Features Photo Zoom
White Subject, Vernal Fall, Yosemite: A spot meter reading off the most important highlight, the white water, indicated 1⁄125 sec. at ƒ/11. A white subject like this is a perfect candidate for Zone 7, so I opened the aperture two stops to ƒ/5.6, placing the water on Zone 7—light, but not washed out. (An in-camera spot meter should indicate +2.0, or two stops of overexposure, for Zone 7, as shown here.)

Zone System Exposure For Digital Cameras
The Zone System requires a spot meter and full manual exposure mode. While a handheld spot meter is preferable, you can make do with your camera’s built-in spot meter mode. If you’re using the camera’s spot mode, try metering with a telephoto lens to narrow the metering coverage appropriately. The simplest approach concentrates on highlights and ignores shadows.

Start by picking the most important highlight—the brightest significant part of the scene that needs to have detail and texture. Then decide what zone that highlight should be. There are really only two choices. Zone 5 isn’t a highlight, it’s a midtone, while Zone 8 is washed out. So that leaves Zone 6 or Zone 7. Use Zone 7 for objects that are white or nearly white, like white water, snow, light sand or very light rock. Use Zone 6 for any other highlight, including tans, yellows or other pastel colors.

Next, spot-meter the highlight you’ve chosen. Make sure the whole spot is filled with a consistent tone; you don’t want a mixture of light and dark areas. To make the highlight Zone 6, increase the exposure by one stop from your meter reading. To make it Zone 7, increase the exposure by two stops. In other words, if the meter indicates 1⁄125 sec. at ƒ/16, lower the shutter speed to 1⁄60 sec. to make that highlight Zone 6 or 1⁄30 sec. to make it Zone 7. (You could change the aperture instead, of course.) Or, while pointing an in-camera spot meter at the highlight, just turn either the shutter speed or aperture dial until the exposure scale indicates one stop of overexposure (+1.0) for Zone 6 or two stops of overexposure (+2.0) for Zone 7.

Autumn Aspens: Applying An S-Curve For Contrast. The original RAW file of these autumn aspens looked flat, but a sharp S-curve increased the contrast and brought it to life.

Zones And Histograms:

This diagram shows approximately how each zone relates to a histogram. The spike at the right-hand edge of this histogram indicates pixels that are overexposed
—Zone 8 or higher. Anything at the far-left edge of the histogram is Zone 2 or lower—black. In landscape photographs, highlights are vital. Usually, the brightest pixels should be near, but not touching, the right edge of the histogram.

Controlling Contrast
The heart of the traditional Zone System is the ability to expand or contract the contrast range of the negative—to increase contrast and add impact to low-contrast images or reduce contrast to hold detail in both highlights and shadows in high-contrast scenes.


Sunset Color, Tunnel View, Yosemite:
Sunrise or sunset light on mountains, or any highlight with color, should almost always be placed at Zone 6, or +1.0, with an in-camera spot meter.

With digital images, increasing contrast is easy. Use Levels or Curves to move the black and white points, and/or make an S-curve. Decreasing contrast is more difficult. While some cameras can capture a bigger dynamic range, that range is fixed and can’t be changed. But by combining exposures, it’s possible to capture detail throughout any scene, with any camera, no matter how great the contrast.

Blending Images: Exposure In The Field

To blend exposures later, you first have to capture all the necessary information in the field. Make sure the camera is on a sturdy tripod to avoid camera movement between frames. Next, use the Zone System, or any method you prefer, to get a good exposure for the highlights. Check the histogram to make sure the brightest pixels are near, but not touching, the right edge, and adjust if necessary.

Then make another exposure one stop lighter, and another, and so on, until you see space between the darkest pixels and the left edge of the histogram. You’ve then captured detail in both highlights and shadows, plus a full range of tones in between. The histograms below show what this might look like.

Histograms For Blending Images: Histograms from four RAW images, each taken one stop apart, capturing highlights, shadows and everything in between.

HDR Vs. Exposure Blending
Ansel Adams used reduced development to capture highlight and shadow detail in high-contrast scenes, but he was well aware that this could lead to flat, mushy areas in the midtones. The same problem confronts digital photographers when blending exposures. Too much tonal compression can reduce local contrast and produce a lifeless image. When comparing different methods of merging exposures, pay attention to those midtones and make sure they have some contrast and snap.

Sierra Foothill Flowers: The first version of this image was blended from five different exposures, each one stop apart, using Photomatix software in its HDR Tone Compressor mode. While there’s detail in the extreme values, the midtones— especially the flowers— appear flat and lifeless. The second image was merged manually in Photoshop with layers and layer masks. This method retained all the local contrast in the bottom two-thirds of the image because the blending only occurred near the top of the frame. The result is a crisper, livelier photograph.

 

Software Solutions
There are a number of software packages that help you manipulate your images using the Zone System. For example, the Ozone filter in Dfx Digital Filter software uses proprietary algorithms to divide the spectrum of the image into 11 zones, each of which can be precisely and independently adjusted. Download a free trial copy at the website: www.tiffen.com/dfx_v2_home.html.

High Dynamic Range, or HDR, uses complex algorithms to combine different exposures and capture detail in highlights and shadows. Exposure Blending takes sections of different images and fuses them together. This could be as simple as using the sky from one photograph and the foreground from another or could involve merging pieces of many images.

I find that Exposure Blending usually produces more natural-looking results than HDR and retains local contrast better, but there are exceptions, so I often try both techniques. For automated exposure blending, Photomatix’s Exposure Fusion option and L/R Enfuse are consistently excellent, but I usually can do a little better by merging the images manually in Photoshop.

Michael Frye’s latest book is Digital Landscape Photography: In the Footsteps of Ansel Adams and the Great Masters, published by Focal Press. Visit www.michaelfrye.com.

35 Comments

    Superb article Michael.Integrating the Zone System into the digital arena effectively has long been a matter of concern. This can only help us combine the convenience of digital with the controls of the past .

    Thanks for your comments Joe and Terry – glad you like the article. You both hit on good points: photography is photography, and the same principles that applied before still work – with some adaptation.

    Thank you for another well-written and insightful piece, Michael. I’ve always appreciated Ansel Adams’ work and certainly appreciate the bridge you’ve built from then to now.

    This was a great article. I’ve tried using the zone system, but never looking for the brightest highlight that I wanted to capture. Instead, I looked for a mid-tone for my spot metering. I’m anxious to give this a try. I assume that in the gorgeous photo on the first page, you would spot meter on the yellowish area and use zone 6? The waterfall is the brightest highlight but appears too small for a spot meter reading.

    I rellay like the artical. If the waterfall highlight area is too small in the photograph above, my experience with light meters would be to expose on the bright clouds (large area) or the sunlit green trees (large area). Do you agree or disagree? Personally I would expose on both the large lighter areas and bracket, pack up my gear, and go to the next viewpoint.

    Michael, this is one of the best articles I have EVER read on exposure. Just the suggestion of how to place highlights on Zone VI or VII was worth the price of admission.

    There have been a large number of lessons offered on using the Zone System for digital, but no one ever offered a practical way to apply it. Until now. Thanks for a great article; that issue of Outdoor Photographer just made it to reference status.

    I just sent a friend a link to this article. If you are going to read a few pages about exposure, then go into the field with a DSLR, I think this is the article that you should read. A superb article in a great issue!

    A great and refreshing article and well writen which gives us new ideas and new things to go out and try,and with a great conectione between the past and the future.well done

    Great information. I guess I’ve been using these techniques for years with digital images without knowing it. I just started dabbling in HDR and combining multiple images to create a single photograph. I’m a photojournalist and cannot use this technique in newspaper photography because it is altering an image but it is fun to experiment and learn from for personal work.

    I’ve been trying to “get it” for some time; how to utilize the zone concept when exposing. I always thought I’d be blowing out highlighted areas. Your article made me give it another try. Using a single exposure and RAW adjustments I’ve been able to really make use of the idea. Thanks very much.

    Good article. I’ve been doing the same spot metering of highlights for a while. However, I think it should be said that different camera brands and models meter differently from on another. For instance, with my Sony A900, metering highlights at +2.5-3.0 (at or near zone 8) works, because Sony designed the camera with a particularly long highlight rolloff. My point is, basically, that one should take the ideas of this article and apply them to how they work with their own camera, as many cameras behave a little differently.

    Thanks for all the comments everyone, and sorry I didn’t check back here sooner!

    David, you’re right, the waterfall is too small, so I’d spot meter the yellowish area just below the middle of the photograph and call it Zone 6. Then of course I’d look at the histogram and adjust if necessary.

    GH, your point about different cameras is well taken. I didn’t have space to go into it with this article, but some cameras have more dynamic range than others. I wrote the suggestions about Zone 7 with most digital SLRs in mind, but with some cameras you might be able to expose highlights at Zone 8 and still retain detail. I recommend testing your own camera to see its capabilities.

    Great Article – and something to work with.

    On another note – you’ve got to shore up aqainst comment spam. None of those last 30 something comments would have made the light of day on my blog – and they sure try.

    Here elaborates the matter not only extensively but also detailly .I support the write’s unique point.It is useful and benefit to your daily life.You can go those sits to know more relate things.They are strongly recommended by friends.Personally I feel quite well.

    I would like to understand more about how to use layers and layer masks to produce the result Michael got in the “foothill flowers” example, using Photoshop vs. Photomatix.

    Michael, nice article…

    The one question I have is if you are considering RAW processing capability on your highlight placement?

    With RAW processing, you should be able to place significant highlights into Zones 8 or, even, 9…just being sure that none of the colors are blown. Most cameras, today, provide RGB histograms and “blinkie” to spot areas that may be problems.

    While in the initial jpeg the highlights may appear washed out, this is easily adjusted…but now you will have reduced noise info in the blacks to work with.

    This would give quite a bit more dynamic range capture and reduce the need take multiple shots for blending or HDR.

    John

    Great article, Mike! Thank you. The one comment I would make is concerning the bracketing of exposures for use in HDR software. I have found it useful to produce one or two further images at even longer exposures than you suggest. This moves the shadow regions of the image into the middle, and even toward the right, of the histogram. The reason for this technique is that digital noise is a lot more prevalent in the darker regions of an image. The HDR software will then pick the dark regions up from the highly overexposed frames and darken them appropriately. The result is considerably less noise in the dark areas, and sometimes a bit more detail.

    Hello Mike, thank you for a great article.
    I have a couple of questions if you don´t mind:
    – What if a have only dark colors, lets say zones III and IV, how should I expose and compensate?
    -If I have only mid tones, zone V, how do I compensate? open two stops?

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