The Zone System Simplified

Although entire manuals, workshops and classes have been devoted to the Zone System, understanding it is really nothing more than understanding how film responds to exposure and development.  The system was codified by Ansel Adams and further expounded upon by Minor White and other modernist photographers.  Some photographers employ it meticulously in their work to ensure “perfect” negatives that yield beautiful prints with a full tonal range.  Many other photographers simply employ its principles with varying degrees of precision in order to make intelligent decisions, based upon lighting conditions at the time of photographing, about exposing and developing the film so that the quality of their negatives is maximized.  Better negatives means using your efforts in the darkroom for creative control and embellishment of the print, rather than compensating for deficiencies in the negative.  Many photographers who claim to know nothing or care nothing about the zone system still employ it in one form or another.  Although the system originated in the context of large-format black and white photography, it can be applied to b/w roll film and to some extent to color photography as well.

 
 

I.Basic principles:

II. Terminology

There are ten zones, numbered with roman numerous from 0 through IX.  (Thevisual scale below omits Zone O, which is the purest black that the photo paper can produce.)  The lower the number of the zone, the darker the tone to which it corresponds:
Zone O
blackest black that can be produced on the photo paper
Zone I
first separation from pure black
Zone II
very dark with just a little shadow detail
Zone III
dark but with full shadow detail.CRITICAL SHADOW
Zone IV
dark gray, Caucasian skin in shadow, .

Zone V
middle gray, Kodak gray card.PIVOTAL ZONE

Zone VI
light gray, Caucasian skin in sunlight
Zone VII
highlight with full detail, very pale Caucasian skin in sun.CRITICAL HIGHLIGHT
Zone VIII
very white with just a little detail, snow in sunlight.
Zone IX
almost as white as the border of the photo paper


 

Note:the zones printed in bold above are the only ones we are concerned with in metering a scene in order to determine exposure and development.  If we get these five middle zones under control, the others at the ends of the scale will fall into place.  Note that by reading any surface and accepting that reading, the surface will be rendered as Zone V.  By shifting toward smaller f-stops (higher f-stop numbers), you shift the tone of that surface toward the lower, darker zones and by shifting toward larger f-stops (lower f-stop numbers) you shift the tone toward the higher, lighter zones.  This is the concept of placing a particular surface in the scene in a particular zone.

III. Determining Exposure

Here are a couple of methods that you can employ listed in order of increasing accuracy:

(1) Read a gray card or something in the scene of about the same tone and use this as your exposure.

(2) Average the critical shadow and critical highlight:   Read the darkest area in the scene that should record full detail and the lightest area that should record full detail. Sete the exposure directly in-between these two.   For example:

f stops:
2.8
4
5.6
8
11
shadow reading
midpoint – use this stop
highlight reading

(3) Read the critical shadow and close down two stops.   In other words, read the darkest area in the scene in which you want to record full shadow detail, close down two f-stops and use this aperture.

IV. Determining Development: 

The most accurate application of the zone system involves taking two light readings.    First, read the shadow area and close down two-stops as in method (3) above.    Then, take a reading off of your highlight detail, the lightest thing in the scene that should still record full detail).     The distance between the shadow reading and the highlight tells you how much to develop the film. Here’s how:
The basic principle of film development is:   With normal development (N), film can record detail over a range of five f-stops.  Anything other than this “normal” lighting situation will require an adjustment to the development time in order to produce a negative with a full range of tones. The critical highlight, that is the lightest area in the scene in which you want to record full detail, should ideally fall in Zone VII.   If  your light metering indicates that it falls below or above Zone VII, an adjustment to the developing time of the film can shift that highlight so that it does print as a Zone VII highlight.
 
Consider the following three lighting situations:Normal, High Contrast and Low Contrast:

 


Normal Contrast:
Zone I
II
III
IV
V
VI
VII
VIII
IX
f-stops
2.8
4
5.6
8
11
shadow
set at this
highlight
Note that the highlight above is five stops from the shadow. Read the shadow, close down two stops and develop normally.
High Contrast:
Zone I
II
III
IV
V
VI
VII
VIII
IX
f-stops
2.8
4
5.6
8
11
16
shadow
set at this
highlight
Note that the highlight reading above is six stops from the shadow reading.   This requires a compaction.   Reduce development of the film 10-15% in order to retain highlight detail.   The compaction will have the effect of lowering the highlight detail which would otherwise have fallen in Zone VIII down to Zone VII where it belongs.
 
Low Contrast:
Zone I
II
III
IV
V
VI
VII
VIII
IX
f-stops
2.8
4
5.6
8
11
16
shadow
set at this
highlight
Note that the highlight reading above is four stops from the shadow reading.   This requires an expansion.   Increase development of the film 15-20% in order to boost the highlight tone.   With this extra development, the highlight, which otherwise would have fallen in Zone VI, winds up in Zone VII where it belongs.