How to Build and Use a Zone Dial - Large Format Photography. Info

How to Build and Use a Zone Dial
Additional functionality for popular spotmeters
by Ralph W. Lambrecht
fig.1 The customized zone dial for the
Pentax Digital Spotmeter is a visual
reference and will simplify zone
placement. Zone III and VII are
marked to place shadow and
highlight details.
Pentax Digital Spot
Zone Dial
©1998 Ralph Lambrecht
I II III IV V VI VII
The lightmeter became part of the photographer’s
tool-box about 100 years after the invention of photography.
Beforehand, photographers relied on empirical
methods or a set of reference tables to determine
the correct film exposure. Early exposure
meters consisted of a holder for light sensitive paper
and comparison step wedges with increasing densities.
The paper was exposed for a given time to the
same lighting conditions as the scene and then compared
to the step wedge. The step, which was the closest
to the exposed paper in density, gave an indication of
the required exposure. Lightmeters have
come a long way since then and have
evolved to be accurate and dependable
tools, no photographer wants to be without.
A serious Zone System practitioner
has little or no alternative than to use a
spotmeter capable of reading subject luminance
within an angle of 1∞. This narrow
angle of acceptance permits convenient
tonal placement of small but important
subject detail. It may not be a
coincidence that the invention of the
Zone System followed the introduction
of the first spotmeter in 1945.
VIII
IX
Reading the Lightmeter in
Zones
Lightmeters, including spotmeters, are
calibrated to suggest a film exposure,
which will render the subject detail measured
as an average or middle gray in the
print. We refer to this as a Zone V exposure.
Consequently, if a luminance reading
is taken with the meter, and this reading
is used to determine film exposure
without alteration, then we have placed
the subject detail on Zone V. However, if we want
the same detail on Zone IV, then we give 1 stop less
exposure or 2 stops less to place it on Zone III. Alternatively,
a 1-stop exposure increase will place the reading
on Zone VI and so on. This technique is called
zone placement and can be simplified with the aid of
a custom zone dial.
Fig.1 shows a custom zone dial for the Pentax Digital
Spotmeter. Feel free to copy it from the book for
your 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 to
have a variety of educational props at hand when discussing
photography in general and the Zone System
in particular. Over the last few years, I have prepared
many of these tools myself and most have proven to
be very useful aids in my own classes, but the standard
zone dial is by far the most popular. This is at
least partially due to the fact, that the pocket size version
shown here, can be used as a zone calculator and
reference guide, while practicing the Zone System
outside of the classroom. In addition, the use of the
EV scale has reduced the complexity of similar devices
to just two dials, which makes it easier to assemble
and use.
All you need to build your own is a few pieces of
cardboard, the use of a copy machine, some self-adhesive
labels or glue, a small utility knife and some hardware
to hold it together. Feel free to copy the illustrations
in fig.2 from the book for personal use and glue
them to the cardboard. Then carefully cut out the
shapes, laminate with clear foil to give it some protection
and use a bolt, nut and washer combination to assemble
the two dials through the marked center points.
258 Way Beyond Monochrome

8
0
1h
90
1
250
The standard zone dial works well with any
lightmeter, which provides film sensitivity adjusted EV
readings. Most spotmeters do, one exception being the
Pentax 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 negative
zone. Now, take a highlight reading and its EV number
location on the dial will reveal the negative zone onto
which these highlights will fall at normal development.
Taking additional readings, you can estimate zone
placement for various subject areas.
Necessary development corrections can be predicted
from the differences between highlight zone readings
and their preferred values. If, for example, the shadow
zone is read and placed, and the desired highlight for
Zone VIII happens to actually fall onto Zone X, then
an N-2 development is required.
The final decision on exposure can be made from
any aperture/time combination in the window, because
the EV numbers were provided as film sensitivity
corrected values from the lightmeter. In addition, the
standard zone dial provides a valuable overview of zone
placement for the entire scene.
0
I
II
8
2.8
4
5.6
III
Zone Dial
© 1999-2001
Ralph W. Lambrecht
8
9
IV
11
V
f/stop
16
Time
10
VI
22
32
11
VII
45
64
VIII
90
12
IX
X
6
1h
30'
15'
8'
4'
13
14
7
2'
1'
5
15
11
12
IV
4'
13
2'
V
14
VI
1'
30"
15
VII
VIII
15"
16
IX
8"
17
18
4
500
30"
15"
8"
16
10
9
II
15'
30'
I
III
8'
Zone Dial
© 1999-2001
Ralph W. Lambrecht
X
4"
2"
19
20
3
125
60
4"
17
7
6
5
500
4
2.8
4
250
5.6
3
8
125
f/stop
11
60
2
16
30
32
22
Time
1
64
45
15
8
4
0
2
-1
EV
21
2
1
0
30
15
-1
8
4
EV
2
21
1
2"
20
19
18
fig.3
The assembled standard zone dial
provides a handy reference to the
way subject brightness will be
represented 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, the
tonality extremes are shown as black and white points at Zone I•5 and VIII•5.
How to Build and Use the Zone Dial 259