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258 Way Beyond Monochrome

VIIIVIIVIVIVIIIIII IX

Pentax Digital SpotZone Dial

©1998 Ralph Lambrecht

Ho w to Bu ild and Us e a Zone D ia l

Additional functionality for popular spotmetersby Ralph W. Lambrecht

The lightmeter became part of the photographer’stool-box about 100 years after the invention of pho-tography. Beforehand, photographers relied on em-pirical methods or a set of reference tables to de-termine the correct film exposure. Early exposuremeters consisted of a holder for light sensitive paperand comparison step wedges with increasing densi-ties. The paper was exposed for a given time to thesame lighting conditions as the scene and then com-pared to the step wedge. The step, which was the clos-est to the exposed paper in density, gave an indication of 

the required exposure. Lightmeters havecome a long way since then and haveevolved to be accurate and dependable

tools, no photographer wants to be with-out. A serious Zone System practitionerhas little or no alternative than to use a spotmeter capable of reading subject lu-minance within an angle of 1!. This nar-row angle of acceptance permits conve-nient tonal placement of small but im-portant subject detail. It may not be a coincidence that the invention of theZone System followed the introductionof the first spotmeter in 1945.

Reading the Lightmeter inZonesLightmeters, including spotmeters, arecalibrated to suggest a film exposure,

 which will render the subject detail mea-sured as an average or middle gray in theprint. We refer to this as a Zone V expo-sure. Consequently, if a luminance read-ing is taken with the meter, and this read-

ing is used to determine film exposure without alteration, then we have placed

the subject detail on Zone V. However, if we wantthe same detail on Zone IV, then we give 1 stop lessexposure or 2 stops less to place it on Zone III. Alter-natively, a 1-stop exposure increase will place the read-ing on Zone VI and so on. This technique is calledzone placement and can be simplified with the aid of a custom zone dial.

Fig.1 shows a custom zone dial for the Pentax Digi-tal Spotmeter. Feel free to copy it from the book foryour personal use. Once applied to the meter as shown,a light reading can be placed on any zone, providing accurate tonal value placement without calculations.

The Standard Zone Dial

It is very helpful for the student and the teacher tohave a variety of educational props at hand when dis-cussing photography in general and the Zone Systemin particular. Over the last few years, I have preparedmany of these tools myself and most have proven tobe very useful aids in my own classes, but the stan-dard zone dial is by far the most popular. This is atleast partially due to the fact, that the pocket size ver-sion shown here, can be used as a zone calculator andreference guide, while practicing the Zone Systemoutside of the classroom. In addition, the use of the

EV scale has reduced the complexity of similar de-vices to just two dials, which makes it easier to as-semble and use.

 All you need to build your own is a few pieces of cardboard, the use of a copy machine, some self-adhe-sive labels or glue, a small utility knife and some hard-

 ware to hold it together. Feel free to copy the illustra-tions in fig.2 from the book for personal use and gluethem to the cardboard. Then carefully cut out theshapes, laminate with clear foil to give it some protec-

tion and use a bolt, nut and washer combination to as-semble the two dials through the marked center points.

fig.1 The customized zone dial for the

Pentax Digital Spotmeter is a visual

reference and will simplify zone

placement. Zone II I and VII are

marked to place shadow and

highlight details.

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How to Build and Use the Zone Dial 259

The standard zone dial works well with any lightmeter, which provides film sensitivity adjusted EV readings. Most spotmeters do, one exception being thePentax Digital Spotmeter, which needs an alternative

zone dial as shown in fig.1. Take a shadow reading and place its EV number next to the desired negativezone. Now, take a highlight reading and its EV numberlocation on the dial will reveal the negative zone onto

 which these highlights will fall at normal development.Taking additional readings, you can estimate zoneplacement for various subject areas.

Necessary development corrections can be predictedfrom the differences between highlight zone readingsand their preferred values. If, for example, the shadow zone is read and placed, and the desired highlight forZone VIII happens to actually fall onto Zone X, thenan N-2 development is required.

The final decision on exposure can be made fromany aperture/time combination in the window, becausethe EV numbers were provided as film sensitivity corrected values from the lightmeter. In addition, thestandard zone dial provides a valuable overview of zoneplacement for the entire scene.

    1    0

      9

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fig.3 The assembled standard zone dial

provides a handy reference to the

way subject brightness will berepresented in the final print.

fig.2 Only two disks are required to make the standard zone dial. Zone III and VII

are marked to place shadow and highlight details, and in addition, thetonality extremes are shown as black and white points at Zone I•5 and VIII•5.

10 9  8

   7

    6

      5

        4

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   '    8   '   1    5 '   3   0'

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8 

1  5  

3   0   

6    0   

1     2     5     

2        5        0       

 5  0  0 

     E     V

Zone Dial© 1999-2001

Ralph W. Lambrecht

16118  

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f/stop

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