The Zone System.

Ansel Adams: "The Zone System"

The Zone System is a method of understanding and controlling the exposure and development of the negative, and how to vary that exposure to get the desired results.

Printing, exposure and developing are all interconnected. The results from one, can be affected by the other. This gives reason to the fact that, the more precise your exposure, the less you will have to compensate during the development and printing stage.

The Zone system was developed by Ansel Adams and Fred Archer as a simple and straightforward procedure by which a photographer could control exposure. Before this procedure came into affect. The photographic industry had already developed and standardised f-stops and shutter speeds as a method of controlling light. But this posed a dilemma for the more experienced photographer. And a lot of them began to ask the question; "How much light must fall on the negative in order to get the photograph I want".

The zone system recognizes the limitation of film and the digital image processor and it works within these limitations to accomadate for the vast amount of colours, tones and brightness variations found in nature and around us. By applying the zone system and utilising its scope in photographic practice, we are able to produce images which exemplify its precise accuracy. We are then able to reproduce images of nature with a wider tonal range and varying degrees of brightness with only a slight unnoticeable difference to that of the original.

Archer and Ansel used the spectrum of print values, from black to white, using f-stops as the standard of measurement. They assigned a zone to each value that each f-stop of exposure produced. This produced what is known as the "Zone Scale". A visual representation of print values from black to white.

The camera is calibrated to take a reading of 18% grey as spot on correct and accurate. The camera will assume that this is the desired amount of light reflectance. It will then average the light reading of the extreme shadows or highlights to produce an over-exposed or under-exposed image. The Zone System eliminates this problem by assigning these specific values to each zone.

A light meter averages the value of all light it receives. Based on this average of light it then assigns a suggested setting (Shutter speed / f-stop), which results in the same exposure. This will be an exposure for a mid grey, which Ansel and Archer classified into Zone V.

The standard eleven are the most commonly used by photographers. The meter reading is in the middle of the scale. The zones are numbered 0 through to X. Zone 0 representing the maximum black that the print can produce. Zone X represents pure white - no image. The nine zones between are each equivalent to one increasing f-stop of exposure. Decreasing or increasing in value from Zone V. The Zone system is the print value that will be produced when the film is properly exposed and developed for that zone. The photographer will then determine the exposure, and the exposure will then determine the zone he will get. The photographers main starting zone will be the zone value V. The Zone System scale is a series of tonal values each value being the equivalent of one full f-stop.

The eleven Zones:

0:- Black, no texture or detail, pure black.

I:- Near black, shadows in faint light or rooms without light, beginning of gradation.

II:- Dark coal-black only subtle textures are visible.

III:- Very dark grey - distinct shadow texture is visible, dark shadow.

IV:- Medium dark grey - slightly darker skin, dark foliage or shadows in landscapes.

V:- Medium argy 18% grey - darker "white" skin or lighter "black skin," light foliage or the dark blue of a clear blue sky. (Your meters suggested reading)

VI:- Rich mid tone grey, average "white" skin or shaded areas in snow on a bright sunlit day, sharp fine detail visible.

VII:- Bright light grey, highest zone that will still hold detail, weathered paint work, silver hair, a concrete walkway in sunlight.

VIII:- Light grey - white, shows last texture at least a minimum, but no detail, reflected highlights from the light coloured skin, gradation still exists.

IX:- Key white or pure white, snow in the bright sunlight, no detail or significant texture visible, lightest gradation values.

X:- Paper base white, no image recorded in print.

How to use and put the Zone System into practice.

Lets say for example I wanted to photograph a perfectly smooth round white stone. I have my spot meter with me and I meter the stone. I would then set my camera controls with the exact same specifications given to me by the spot meter. Am I doing this correct? According to Ansel Adams Zone system, my meter will give me a reading for a dull 18% medium grey. This isn't correct, as I know by looking at the pure white stone. That's if I take this reading at face value and input it into my camera. If a take a picture, the printed exposure for that image will portray the white stone as dull medium grey. I don't like this result, it is not a accurate indication of the physical features of the stone. But, if I follow the above procedure as layed out by Ansel Adams, my pure white stone should be at VIII ( Light grey -white showing some texture as a minimum) but my meter is indicating Zone scale V. I will then need to give the pure white stone more exposure than indicated by the meter. I open the lens three f-stops from that which was suggested by the meter. This will place my setting at VIII. The pure white stone has remained a constant, that is a given. All I have done is changed the exposure. I am trying to establish the tonal value by using Ansel Adams Zone system procedure. I have mentally visualized the changes in the tone value for the print as I change the exposure. Either going up or down from my starting point zone V.

Another example would be if you where up in the Lake district during the winter season. You want to photograph the snow covered peaks. Similar to the above mothod. You will also take a meter reading for the snow, which gives off a suggestion shutter speed of 1/500 and a corresponding aperture of f/16. Now according to the Zone system, if you use these setting. The image will be a dull 18% grey "Zone V". The Zone System indicates that snow in bright light falls within Zone IX. This is four stops below Zone V (the 18% grey). It would then be logical to open up four stops to f/4 and shoot at 1/500. This will give the image a more natural white snow appearance.

However, the Zone System is not limited to a single object. Our world consists of different scenes. Take for ease of understanding the procedure. The above example of the Snow covered peaks in the Lake district. Now these peaks will be surrounded by a bright blue sky, white clouds in the background. The peak area with have various rock formations of different colour densities. As a photographer, I want to capture as much detail as possible, espcially the different rock formation densities and the shadows. I meter for the shadowed areas of the rocks. This gives me a reading of 1/60 with a corresponding aperture of f2.8. I want to capture that bright blue sky, so I take a second reading, which gives the same shutter speed but a different aperture of f/16. I have mentally visusilised that this scene has high and low levels of contrast, so I will need to expose to show the shadows to capture the detail in these different tones. Using the Zone system, I can verify that the shadowed areas of my scene fall into Zone II. In order to capture this scene, I will then need to be three stops and shoot at 1/60 at an aperture of f/8. But this will result in me losing a lot of the highlight details of the bright blue sky. This isn't really what I want. It doesn't achieve the desired result I initially wanted.

This brings me to the second part of Ansel Adams's Zone System. The Zone system incorporates exposure and development techniques. By varying the development time, to a certain degree plus or minus according to the given f-stop scale. Using Ansel Adams procedure, we will then be able to control Zone placement by controlling development of the negative. As developing time is increased, negative densities also increases. This will also increase our highlight densities within our image. So it gives reason to state that contrast increases with increased developmet time. This will be obvious. So from this we can determine that highlight density is controlled by developing time and shadow density is controlled by exposure. So it would be logical to assume that any additional developing time would cause "over developing" causing the highlights to move up the Zone System scale two zones. And without stating the obvious, lowering the highlight densities with bring it down two zones.

But as Ansel Adams used large format "Sheet" film which gave him more control over the development of each negative. Allowing him to isolate each section of the negative and varying its development. This is all very good, but what if you are a digital photographer. The Zone system will still apply and you can utilize both the dodge and burn techniques. Dodging is when a photographer uses a specfic software package like Adobe Photoshop to lighten certain areas of the image. Burining refers to the darkening of specific areas.

A digital zone system:-

Zone 0 = -5EV (pure black no detail) - black nighttime skies.
Zone 1 = -4EV (black, only a few details present) - very dark shadows.
Zone 2 = -3EV (black with some detail visible) - dark shadows, black clothing.
Zone 3 = -2EV (dark but full detail present) - blue sky, dark green leaves, dark skin.
Zone 4 = -1EV (dark tones with full details visible) - dark skin, general appearance.
Zone 5 = 0EV (middle tone 18% full details visible) - light skin, stone washed jeans.
Zone 6 = +1EV (light tone but with full details visible) - light skin.
Zone 7 = +2EV (white with some details present) - paper, white walls.
Zone 8 = +3EV (white with a hint of detail present) - overexposed, pure white backgrounds.
Zone 9 = +4EV (pure white no details present) - reflections, lights.

If your spot meter gives you a reading of a middle 18% tone grey "0EV". If you aimed it at a grey card, and the meter didn't read for a "0EV", you will needed to adjust the exposure until the meter read "0EV". By doing a few tests using a piece of white paper instead of a grey card. You will be able to find that the white paper is 2 stops brighter than the grey card (+2EV). And you will need to adjust for this as your meter will give off a reading of +1.3EV. So logic will dictate that you amend this by adjusting it until it read +2EV. This results in a longer exposure which in turn will produce a brighter image. This can only mean one thing. That Ansel Adams's Zone System can be applied digitally to assign exposures to scenes with a known brightness.

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Ansel@ Struthers Web 2010