The Digital Zone System

"Zone System" : A long established method, pioneered by Ansel Adams, to get the maximum tonal range from a photograph. What is the Zone System ? In 1940, Adams, together with Fred Archer, pioneered a technique whereby the tonal range, or more precisely the deepest shadows and brightest highlights, of a scene could accurately and consistently be recorded onto film and prints by means of exposure and development control. This system also allowed Adams (who went on to perfect the system) to be able to choose the zone placement of a metered object and adjust the film development to maximize the tonal values of that metered object. Simply put, maximum tonal values regardless of the conditions under which the photograph was made, with no loss of detail in the shadows or highlights. The Zone System created by Adams allowed him to express his emotions and feelings through his visions which still are valued, practiced and cherished by today’s photographers. Adams was a quiet, gentle man, showering accolades upon him was futile, he would not accept the honors which were due to him for his pioneering work. Rather, his driving passion was to preserve the natural beauty he found in the wilderness. His favorite locations were Yosemite and the High Sierras in California. So deep were his feelings that he went to Washington and lobbied for preservation on a national level. Adams was also an accomplished musician, capable of playing the most difficult classical music. Typically there are 10 “zones” represented in this system. Modern films have a dynamic range of 8-9 stops. For our discussion here we will say that a stop and a zone are the same thing. The terms are interchangeable. 1 stop equals 1 zone. So how can we fit 8-9 stops into 10 zones? We don’t because pure white and pure black don’t count, ignore them for now. What we want is 8-9 stops or zones to be visible in the print. Here is the scale for a 10 stop range:

How does that translate into a photograph? Let’s look at a photograph illustrating the Zone System results: This is a typical scene and represents a full range of Zones. Ideally, we should aim for this range in all our work, whether in bright sun or dark stormy weather, indoors or at night.  The important elements in this scene have been outlined in red for you.

Here are further examples of varying conditions under which the Zone System can be utilized.

You will see that this photograph contains large amounts of black area’s but at the same time exhibit’s a full range of zones from deepest black to specular white. By using Adams Zone System I was able to meter the separate area’s in the scene, place them within the zones, developed the film accordingly, and produced a sparkling print of the scene with no loss of detail.

Below is a studio shot of a camera. In reality studio work also lends itself to the Zone System. However, it is much easier to employ this technique under controlled lighting. We can adjust the lights to achieve the required results, and ensure that the photograph will be well suited to printing with minimal effort.

For this photograph below there were several considerations to be made. The light was constantly changing, faster than I was able to take several meter readings. Under these circumstances it would be wise to meter the scene with “Average Metering” and develop the film normally. There are only a few very small white area’s in this scene and for all intents and purposes can be ignored. What we really want is to preserve details in the darker area’s of the photograph. This photograph would be printed using further darkroom techniques employing contrast specific paper or burning and dodging techniques to bring out the tonal values as specified in the Zone System.

Conversely, we may encounter a scene whereby the tonal values are biased at the highlight end of the scale as shown below. We must still capture the darkest shadows while maintaining detail in the highlights. For this photograph we must take into account which detail will fall into the highest zone capable of recording a detailed white. My aim point for this shot would be Zone 9+, the tops of the protruding wall parts. By doing so, all the values are represented, from high whites down to a nice rich black.

Here is an example of a night scene. You will see that even at night we can employ the Zone System  to achieve a long tonal range in our photographs from the deepest blacks to the brightest whites. In the shot below I was willing to let the sky go deep black as there were no real points of interest. We can see the power poles behind the locomotives because they are not the same tonal value as the darker sky.

Summarizing The basic thing to remember when shooting shots like the above examples  is that you should use the Spot Meter option in your camera to take readings of all the important elements in your scene. I am assuming at this point you have that option available to you. You will also note that the only way to employ the Zone System is to use Manual Exposure Mode on your camera so that you can vary the exposure according to the meter readings and not have the camera over-ride the settings you wish to employ. The two most important measurements you can make will be the brightest highlight and the deepest shadow in which you want to see detail. These two readings determine whether or not they can be recorded on your medium. Of course, you will have the choice of just how many area’s within the scene you are willing to disregard. If we assume that the highlights and the shadows will be included within the range offered then all will be well. We can be confident that the tones between the highlights and shadows will be recorded. We must be aware that the dynamic range should not be exceeded if we are to retain details in our photograph. For film you can expect a range of 8-9 stops or zones. For digital camera’s you can expect a range of 5 stops or zones. Film users have the option of development control to help them in obtaining the full dynamic range offered by using the Zone System. By careful metering and knowing in advance where they want to record a particular tonal value on the scale, they can then develop the film to a pre-determined level and be confident that the tonal range will be reproduced in the negative.

The Digital Age Now that we have a very basic understanding of the Zone System the question arises, “Can we carry the traditional Zone System forward into this new era of photography?”. After browsing the internet and reading some interesting views on various websites I have come to the conclusion that indeed we can. The tools we use may be very different than Adams used, but in essence we are aiming at the same Zone System.  The traditional darkroom has been replaced by computers and software. No longer are we to spend hours working in semi darkness. Gone are the days when a photographer had to be a master technician, knowing his tools of the trade, knowing the nuances of developing film, making a fine art print in the traditional sense, sometimes taking several days to complete. I say this with tongue in cheek. Just how much progress have we made? With the advent of the digital camera we have at our fingertips a more powerful tool when combined with highly specialized software. Software has taken the place of the darkroom. Today, we can make a photograph and within moments view that same photograph on our computer screen in glorious color. There are proponents of each media who will argue for one media against the other, in my mind there is no better way, each has a place. However, I am able to draw a parallel between the darkroom and software. That is to say, they both achieve a finished print in much the same way. When we make a photograph we are basically concerned with contrast whichever medium we choose. Today’s software  gives us a myriad of controls to help us achieve a well balanced and pleasing print. I am not going to go into specifics of individual software, there are numerous websites where you can find specific information regarding your software and what tools are included with that software, rather, I will generalize on the method of obtaining a pleasing or fine print. If we are to achieve results similar to the Zone System we must first consider a couple points. The main consideration would be that a digital camera can generally only encompass a 5 stop or zone range compared to film’s 8 or 9. That, in itself, places the digital camera user at a disadvantage. A 5 stop range requires us to be even more critical when taking a meter reading of the scene. The Zone System scale has been replaced by what is called a “Histogram”. The Histogram and the Zone System scale are in essence the same thing. Today’s Histogram is more precise than the Zone System in as much that it displays the tonal range of the image in 255 steps rather than the 10 steps of the Zone System. When looking at the Histogram we will see a series of vertical lines. These lines are arranged according to the distribution of the tonal values within the scene. In the second diagram we can see how these vertical lines are arranged or distributed within the zones.

If we wish to compare digital with film we must use what is termed “RAW” format using the camera quality settings prior to making the photograph. This RAW format is the equivalent to the film negative in today’s digital camera. The image is captured in it’s RAW state, without alteration of any kind by the camera. In our discussion we will assume that the photograph is still in it’s “latent” form when processed to the compact flash card by the camera. The camera has in effect just transferred information, pixel by pixel, as was viewed by the lens. If we think about this process for a while, we will see that it is identical to image capture on film. Silver Halide crystals have been replaced by pixels. Silver Halide crystals and pixels both accomplish the same task. They absorb light, albeit in a different manner. Pixels can be re-arranged after the photograph is taken, Silver Halide crystals cannot. Digital cameras have one serious advantage over film camera’s when using the RAW format. When we open the latent image in our software program we are still able to manipulate the image with regard to the basic exposure used to make the photograph. Several tools will be available which allow us to manipulate the image. One of the most common tools is the “Curve” control tool. You will see that there are three small triangles under the distribution of tones.

We already know that Shadows are on the left, and Highlights are on the right. These triangles are commonly referred to as “Sliders”. You can move each one separately, either in a left or right direction. By moving those sliders we are in fact emulating Adams Zone System. What is basically happening is that we are expanding or contracting the tonal range of our photograph just as Adams was doing. The difference becomes clear when we consider that Adams system relies on achieving a perfect exposure prior to tripping the shutter which then would receive a pre-determined development. In digital photography, we have the luxury of a “second chance” to get that perfect exposure through software manipulation. We also have the luxury of viewing a positive image on our screen, film does not offer that “feature” and relies on the photographer to interpret the negative image to bring about that final print. If you care to try it, convert your image to “Negative” and then make your corrections. You will find out in a hurry, it’s not so easy. Today’s photographer is now free of the darkroom and it’s gloomy environment. We can now work in complete freedom either in a computer designed workstation full of the latest gadgets that technology allows, or simply a laptop computer perched precariously on our lap. There are many fine websites out there that encompass the use of various tools that manipulate a digital image, more specific in nature than this essay. My suggestion would be to search them out, use this essay to spark your imagination and set you on the road to finding “A Perfect Print”.

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