ExpoImaging Medium Format Film User Manual

V. 01 SEP 05

ExpoAperture Depth of Field Guide

MEDIUM FORMAT FILM INSTRUCTIONS

120/220 film square format

Using the ExpoAperture Depth of Field Guide with medium format film (120/220) is very simple;
you either multiply or divide the number of zones by two as you switch from one side of the
Guide to the other. If starting on the front of the Guide multiply the number of zones by two and
then use that number of zones on the Zone Dial. If starting on the Zone Dial divide the number
of zones by two and then use that number of zones on the front of the Guide.

Example 1: Determine the appropriate aperture setting and focal point to
produce a given depth of field, such as 7½ feet to infinity, using a 100mm
focal length lens.

1.a On the Zone dial (the back of the
Depth of Field Guide) determine how
many zones need to be in focus.

For 7½ to infinity to be in focus,

four (4) zones are required.

1.b Determine the mid-point of the zones
to obtain the required focal point.

The mid-point is 15 feet

Focus your lens at 15 feet

1.c Divide the number of zones by two
(2).

The number of zones is now 2

1.d On the front of the Depth of Field
Guide set the dial to the actual focal
length of your lens.

100mm

1.e Read the required aperture setting
above the number of zones
determined in step 1.c above.

Using 2 focus zones

The required aperture is f32

Copyright 2005 Expoimaging, Inc. All Rights Reserved

Example 2: Determine the depth of field obtained when using a specific focal
length and aperture setting using a 120mm focal length lens, f22 aperture,
and focal point (subject) distance of 10 feet.

2.a On the front of the Depth of Field Guide
set the dial to the actual focal length of
your lens.

120mm

2.b Read the number of zones on the dial
below the f-stop you want to use.

Using an aperture of f22

The number of zones is 1

2.c Multiply the number of zones by two (2).

The number of zones is now 2

2.d On the Zone Dial (the back of the Depth
of Field Guide) determine the distance to
the focal point (subject).

10 feet

2.e Center the number of zones determined
in step 2.c on your focal point and read
the depth of field.

Using 2 focus zones at 10 feet

The depth of field is…
7½ to 15 feet

Copyright 2005 Expoimaging, Inc. All Rights Reserved