The zone system

Last Updated on Wed, 21 Feb 2024 | Photographic Lighting

Control the resulting tonal range of a black and white image using black and white film.

Learn to previsualize the printed image when viewing a scene.

Test the exposure index of the film you are using.

Test the accuracy of the development you are using.

Create images exposing for the shadows and processing for the highlights.

Introduction

The zone system is a technique of careful metering, exposure, processing and printing designed to give maximum control over the resulting tonal values of a black and white image that has been captured using black and white film. It is an appropriate technique to use on location where the ambient light cannot be altered to suit the contrast and tonal range desired by the photographer. It requires the use of short rolls of film or sheet film as the film processing has to be tailored to suit the subject contrast and lighting quality of each specific image. The system was developed by the famous landscape photographer Ansel Adams. He formulated that just as an octave of audio frequency can be subdivided into notes from A to G#, the tonal range of the image (from black to white) can also be subdivided into tones or zones, each zone being one stop lighter or darker than the next. The zones on the photographic paper can be measured and are not open to interpretation. The zone system can, however, be used to interpret the subject differently depending on the desired outcome by the photographer. The photographer achieves this by choosing how dark or light the highlight and shadow tones will appear in the final printed image. 'Previsualization' is the term given to the skill of being able to see in the mind's eye the tonal range of the final print whilst viewing the subject. The zone system removes any surprise factor involved in the resulting tonal range of the image.

: Arches - Ansel Adams © Ansel Adams Publishing Rights Trust/CORBIS

Benefits and limitations

With practice the photographer needs only to take one exposure to translate the subject into a preconceived image. Ansel Adams did not bracket his exposures. He did not need to. He knew precisely the result that each exposure would produce.

The time it takes to meter the subject carefully limits the use of the system. Images are created using the zone system, not captured. Henri Cartier-Bresson would not have found Ansel's zone system very useful for the images he wished to make.

Zone placement

Many photographers already use one aspect of the zone system when they take a light meter reading. Taking a reflected meter reading from a gray card and exposing the film to that meter indicated exposure is to place a tone (middle gray) to a specific zone (Zone V). The placing of a tone to a specific zone is called 'zone placement'.

To use the zone system fully the photographer must take two readings when metering the subject. One reading is taken from a highlight and one from a shadow. They are chosen by the photographer as the brightest and darkest tones which will require detail when these tones are viewed in the final image. These tones are selected subjectively. Each photographer may choose different highlight or shadow tones depending on the desired outcome. The selected highlight and shadow tones are then placed to appropriate zones.

0 I II III IV V VI VII VIII IX

The zone ruler

The tonal range of the print is of course much greater than just ten tones. Breaking the tonal range into ten precise zones allows the photographer to visualize how a metered tone in the subject will translate into a tone on the printing paper.

A selected tone can be moved up or down the scale one zone at a time simply by opening or closing the aperture one stop at a time. By placing a tone further up or down the scale the image is made darker or lighter as all other tones are moved in the same direction.

Activity 1

Frame a location (one that you can revisit again easily) when it is illuminated by directional sunlight. Approach a broad range of tones, from bright highlights to dark shadows, within the framed image and take a reflected light meter reading from each. Keep a record of each tone and its meter indicated exposure.

Take a gray card reading and bracket three exposures (meter indicated exposure, plus one stop and minus one stop). Process the film normally using the manufacturer's recommended development time, temperature and frequency of agitation.

Make a print from each of the three negatives without burning the highlights or dodging the shadows on medium-contrast printing paper. Using your notes label the range of tones you metered for in the first step of this activity, e.g. you may label a dark tone f4 @ 1/125 second and a highlight as fl6 @ 1/125 second.

Discuss the tonal quality of each print with other students, e.g. can you see detail in the highlights and shadows?

Contrast control

The individual tones within the subject can be moved closer together (lowering the contrast) by reducing the processing time, or moved further apart (increasing the contrast) by increasing the processing time. Decreasing the processing time decreases the density of the highlights on the negative whilst leaving the shadow tones relatively unaffected. Increasing the processing time increases the density of the highlight tones on the negative whilst leaving the shadow tones relatively unaffected. There is some effect on the mid-tones in both instances but proportionally less than the highlights.

If shadows are missing from the negative (areas of clear film base within the frame) then no amount of extra development will reveal detail in these areas.

Negative with good detail

Contrast exceeding the latitude of the film

Negative with good detail

Contrast exceeding the latitude of the film

Subject brightness range

The photographer can measure the contrast of the subject (subject brightness range) and then alter the processing of the negatives according to the desired contrast. The photographer exercises precise control by measuring the distance in stops between a highlight tone and shadow tone. If the distance between the selected highlight and shadow tones is greater than four stops (extreme contrast) processing can be decreased to lower the contrast of the image. If the distance between the selected highlight and shadow tones is less than four stops the processing can be increased to increase the contrast of the image.

Summary so far

~ The zone system is made up of ten major tones from black to white. ~ Each tone is one stop darker or lighter than the next.

~ Specific highlight and shadow tones of the subject are assigned to specific zones. ~ Zone placement of a shadow tone is a subjective decision. The decision dictates what detail is visible and how dark these shadows appear in the final image. ~ Development affects highlight tones proportionally more than shadow tones. ~ Increased or decreased processing time leads to increased or decreased contrast. ~ Subject contrast is measured in stops.

~ Shadow tones are controlled by exposure and highlight tones by development.

The zones

Each zone in the final image can be identified by its tone and the detail it reveals. To obtain accuracy we must become familiar with the characteristics of each zone.

Zone IX. Paper white. The standard print utilizing a full tonal range uses little or no paper white in the image.

Zone VIII. White without detail. The brightest highlights in the image are usually printed to this zone.

Zone VII. Bright highlights with visible detail or texture. If highlight detail is required it is placed in this zone by calculated processing time.

Zone VI. Light gray. Caucasian skin facing the light source is usually printed as Zone VI.

Zone V. Mid-gray with 18% reflectance. A meter indicated exposure from a single tone will produce this tone as a Zone V on the negative.

Zone IV. Dark gray.

Shadows on Caucasian skin are usually printed as Zone IV.

Zone III. Dark shadow with full detail and texture. If shadow detail is required it is placed in this zone by calculated exposure.

Zone II.

Shadow without detail.

Zone I. Black.

Zone O.

Maximum black and is indistinguishable from Zone I in the printed image.

Activity 2

Refer back to the three prints created for Activity 1.

Select the image with the broadest range of tones (best exposure).

Label this image with the zones from I to IX. Use the description of each zone on this page to help you identify each zone.

Compare and discuss your labelled image with those of other students.

essential skills: photographic lighting Zone recognition

Using the description in the previous section we are now able to recognize what each zone looks like in the printed image. Zones III and VII are of particular interest as they will indicate the accuracy of how a photographer has utilized the zone system. Important areas of shadow and highlight detail will have been preserved whilst still utilizing Zones II and VIII to give the print both depth and volume.

Zone III

Zone VII

Zone III

Zone VII

Dark shadow with full detail and texture. If shadow detail is required it is placed in this zone by calculated exposure.

Bright highlights with visible detail or texture. If highlight detail is required it is placed in this zone by calculated processing time.

Operating the system

Gaining maximum control over the system requires practice. The student should take notes and compare the results with the actions taken. Mistakes may be made initially but these mistakes will lead to a greater understanding of the system.

Testing the accuracy of exposure and negative processing is crucial to obtaining precise control over the zone system. The photographer is advised to limit the combined choice of camera, light meter, film, developer, enlarger and printing paper until this control has been achieved, otherwise variations in outcome are inevitable.

Jana Liebenstein

Choice of camera, light meter and film

Use a camera and a light meter that provide accurate exposures. If the camera or meter receives a shock through impact, the equipment should be checked. Some retail outlets will offer to test the accuracy of the equipment.

Select only one type of 100 ISO film until control has been achieved. The student should ideally have some experience of processing this film prior to using it for the zone system. Establish an 'exposure index' for the film (see activity below). The usable speed for the film may vary from the manufacturer's recommended speed due to a variety of reasons.

Activity 3

Using black and white negative film, take several exposures of a subject with a four stop range. Someone wearing a white shirt with dark trousers or jacket would be ideal. Calibrate the exposure using a reflected light meter reading taken from a gray card. The subject should be illuminated with diffused light (cloud cover or shade). Bracket the exposures (1/3 stop intervals) keeping a precise record of each frame.

Process the negatives according to the manufacturer's specifications.

View the negatives on a light box and choose the best exposure with the assistance of an experienced practitioner. The darkest tones of the subject should render full texture and detail

(no area of the image should appear clear).

Choose the best exposure and check your records to find the degree of compensation required. For example, if the best exposure for accurately rendering shadow detail is 2/3 stop more than the manufacturer's recommendation of 100 ISO then proceed to rate the film at 2/3 stop less, i.e. 64 ISO.

essential skills: photographic lighting Exposure and processing

The zone system can be approached in a series of sequential steps. The entire system can be divided into two main practical skills. These are:

~ Exposing for the shadows. ~ Processing for the highlights.

Exposing for the shadows

View the subject and choose the dark shadows that you want to be able to see full detail and texture in when you view the final image. Take a specific reflected light meter reading from one of these dark shadow tones. Use a hand-held meter at close range or fill the frame of a 35mm SLR with the selected tone. Use a spot meter to isolate a tone from a distance. Place the shadow tone in Zone III by stopping down two stops from your meter indicated exposure or MIE (e.g. if the light meter reading of the shadow tone is f4 @ 1/125 second then the final exposure could be f8 @ 1/125 second). This action is called 'exposing for the shadows'.

: Metering for the shadows and processing for the highlights

Processing for the highlights

View the subject and choose the bright highlights that you want to be able to see full detail and texture in when you view the final image. Take a specific reflected light meter reading from one of these bright highlights. Measure how many stops brighter the highlights are than the shadows metered for in the previous step. If the shadow tone meter reading was f4 @ 1/125 the highlight tone may measure f16 @ 1/125 (four stops difference).

For bright highlights to record as bright highlights with full detail and texture they must fall in Zone VII (four stops brighter than the shadows). If this is the case the negatives can be processed normally. If the highlights measure more or less than four stops, decrease or increase processing time accordingly (see 'Compression' and 'Expansion').

Adjusting the development time

It is recommended that 'one shot' development (tank development using freshly prepared developer which is discarded after the film is processed) is used in conjunction with a standard developer. Developers such as D-76 and ID-11 are ideal for this test.

The student should use the same thermometer of known accuracy (check it periodically with several others) and adhere to the recommended development times, temperatures and agitation. A pre-wash is recommended to maintain consistency.

Viewing the negatives - the highlights of a high-contrast subject should be dark but not dense when the negatives are viewed on a light box. Newspaper print slid underneath the negatives should easily be read through the darkest tones of the image. Manufacturer's numbers and identifying marks on pre-loaded film should appear dark but not swollen or 'woolly'. The student should view the negatives in the presence of an experienced practitioner to obtain feedback.

Compression

If the selected highlights measure five or six stops brighter than the shadows placed in Zone III they will fall in Zone VIII or IX respectively. No detail will be visible by processing and printing the negative normally. The highlight tones selected can be moved one or two zones down the scale to Zone VII by decreasing the processing time. This situation is often experienced with a high to extreme subject brightness range (SBR).

Moving the highlights one zone down the scale is referred to as N-1, moving the highlights two zones down the scale is referred to as N-2. N-1 negatives are processed for approximately 85% of the normal processing time, N-2 negatives for approximately 75% of the normal processing time when using 100 ISO film. The action of moving highlight tones down the zone scale is called 'compaction' or 'compression'. Shadow tones remain largely unaffected by reduced processing time so the final effect is to lower the contrast of the final negative.

Expansion

If the selected highlights measure only two or three stops brighter than the shadows they will fall in Zone V or VI respectively. Highlights will appear dull or gray if the negatives are processed and printed normally. The highlight tones selected can be moved one or two zones up the scale to Zone VII by increasing the processing time. This situation is often experienced with a low SBR or flat light.

Moving the highlights one zone up the scale is referred to as N+1, moving the highlights two zones up the scale is referred to as N+2. N+1 negatives are processed for approximately 130% of the normal processing time, N+2 negatives for approximately 150% of the normal processing time when using 100 ISO film. The action of moving highlight tones up the zone scale is called 'expansion'. Shadow tones remain largely unaffected by increasing the processing time so the final effect is to increase the contrast of the final negative.

Calibration tests

The following additional tests can be conducted to check the accuracy of exposure and processing time.

Note > Changing printing papers or type of enlarger (diffusion or condenser) will change the tonal range and contrast that can be expected and so therefore should be avoided.

Exposure

The exposure index is calibrated by checking the accuracy of shadow tones on the negative. This can be achieved by using a 'densitometer' or by conducting the following clip test.

~ Underexpose a gray card by three stops (Zone II).

~ Leave the adjacent frame unexposed.

~ Process the negatives according to the manufacturer's specifications.

~ Place half of each frame (unexposed and Zone II) in a negative carrier.

~ Make a step test using a normal contrast filter or grade two paper. ~ Establish the minimum time to achieve maximum black (MTMB). ~ The tone alongside the MTMB should appear as Zone II (nearly black).

MTMB

Zone II

If the adjacent tone to the MTMB exposure on the test strip is too light (dark gray), decrease the exposure of the film. If the adjacent tone to the MTMB exposure on the test strip is too dark (black), increase the processing time.

Processing

Processing is calibrated by checking the accuracy of the highlight tones on the negative. This can be achieved by using a 'densitometer' or by conducting the following clip test.

~ Overexpose a gray card by three stops (Zone VIII).

~ Leave the adjacent frame unexposed.

~ Process the negatives according to the manufacturer's specifications.

~ Place half of each frame (unexposed and Zone VIII) in a negative carrier.

If the adjacent tone to the MTMB exposure on the test strip is too light (paper white), decrease the processing time of the film. If the adjacent tone to the MTMB exposure on the test strip is too dark (Zone VII), increase the processing time.

Activity 4

Choose a 100 and 400 ISO film and conduct the exposure and processing tests as outlined on these pages.

Discuss your findings with other students.

Perfecting the system

For accurate previsualization the photographer must be familiar with all the materials and equipment in the chain of image creation. A common mistake is choosing a few very dark shadows to place in Zone III and the brightest highlights to place in Zone VII. The result may be a flat low-contrast image with the majority of the image placed in only three zones. Each time the system is operated the individual's ability to accurately previsualize the outcome improves.

Summary

~ Take a reflected meter reading of a shadow tone. ~ Place in Zone III by closing down two stops. ~ Take a reflected meter reading of a highlight tone. ~ Calculate how many stops brighter the highlight is than the shadow. ~ Calculate the processing time using the information below.

Average processing adjustments for 100 ISO film

Contrast Processing time %

stops	brighter	than	Zone	III	N+2
stops	brighter	than	Zone	III	N+1
stops	brighter	than	Zone	III	N-1
stops	brighter	than	Zone	III	Activity 5 Revisit the location you photographed in Activity 1 at the same time of day with the same lighting (directional sunlight required). Using the zone system create an image with a full tonal range. Choose the shadow and highlight details you wish to place in Zone III and Zone VIII. Expose, process and print the negative to obtain the final image. Compare the results achieved in this activity with the image created for Activity 1 and discuss the visual qualities with other students. A black and white digital workflow It is possible to create high quality black and white images using a digital workflow as well as the more traditional analog film and photographic paper route. Just as the Zone System is about tonal control and manipulation we can exercise the same degree of precise control over digital tones or levels destined to be printed via an inkjet printer. This control can be exercised during the capture, post-production editing and printing stages of the digital process. Capturing in RGB It is important to capture the images destined for black and white as color images in the digital camera you are using. Do not be tempted to select any black and white option that may exist in your camera's preferences. It is advisable to capture your images using the Raw file format to access the higher bit depth and higher dynamic range that the Raw file format offers. Make sure you have read the section 'Raw format exposure considerations' in the chapter 'Exposure and Light Meters' (pages 51 to 58). To achieve rich shadow tones it will be important not to underexpose the shadow tones during the capture stage of the process. Converting to grayscale in the editing software The best place to convert a digital image from color to black and white (grayscale) is in Adobe Camera Raw or Photoshop Lightroom. Use the sliders in the HSL/Grayscale tab to fine-tune the conversion process. Dragging the red slider to the right will lighten the red colors in the image whilst dragging the blue slider to the left will darken the blue tones. You can then lower the exposure and increase the overall contrast using the tone curve controls to increase the drama further if required. For users of Photoshop Elements it is recommended that you open the image as a 16 Bits/Channel file from Adobe Camera Raw and then make use of the 'Convert to Black and White' adjustment feature to achieve maximum quality. Mode: EPSON Standard_ k Advanced Settings: Mode: EPSON Standard_ k Advanced Settings: Black and white printing using an inkjet printer If you hope to create neutral black and white prints from a color inkjet printer it is important to either profile your printer or consider purchasing a printer that utilizes a gray ink cartridge in addition to the black ink cartridge that is part of the overall ink set. Budget 8 x10 inch (A4) printers usually struggle to print black and white images without a color cast in both the shadow and the highlight tones. The 'canned' profiles that come shipped with these printers rarely produce acceptable results. Attempting to print black and white images using the 'black' option in the printer driver can result in unsightly ink dots in the highlights of the print and the image does not match the luminance values of the calibrated on-screen display in your editing software. Profiling an inkjet printer A calibration device such as the Gretag Macbeth Eye-One Pro from X-Rite is capable of creating a custom profile for your unique printer/ink paper combination. Alternatively you can contact a profile service provider who can create a profile for you using the same hardware. This involves measuring a target print from your printer to create a unique profile for the color characteristics of your printer setup. Normally these profiles are created using no color management as the untagged target file moves through the editing software and the printer driver software. The file is opened in the editing software without converting to the working space ('Leave as is'), 'No Color Management' or 'Same as Source' is then selected in the 'Print' dialog box and the color management is switched off in the printer driver. To create a more efficient profile for a budget printer it is recommended that the color management is left on in the printer driver (the rest of the workflow remains the same). It is important to select a standard color setting in the Color Controls of the printer driver with a Gamma of 1.8, if available. This last step will ensure the shadow tones print with rich detail instead of printing too dark (as is the case with standard profiles created for these budget printers). Note > The larger 13 x 19 inch (A3) printers using the higher quality inksets (such as the Epson 2400 using UltraChrome K3 inks) have better 'off-the-shelf' performance for printing black and white prints with better shadow detail. Target tones With an accurate printer profile optimized for your printer you should be able to target the three most important tones in the Zone System. This is Level 110 which should print approximately the same tone as a photographers' gray card, the darkest shadow tone that is not black (Zone II) and the brightest tone that is not paper white (Zone VIII). Print a step wedge with tones of a known value so that you can accurately assess the performance of your printer, when working with a particular paper and ink combination. Once these values have been targeted in the print you can then accurately target these tones when working with images in your image-editing software (see the texts Photoshop: Essential Skills or Adobe Photoshop Elements Maximum Performance for more information on these post-production skills).