ExpoImaging Medium Format Film - 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
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