LESSON 1
USE AND PURPOSE OF FILTERS IN COPY WORK
TASK
Determine filter functions, selection of filters, and determine filter factors.
CONDITIONS
Given information and diagrams about filters, selection of filters, filter factors, and types of filters.
STANDARDS
Demonstrate competency of the task skills and knowledge by correctly responding to 80 percent of the
multiple-choice test covering filter functions, selection of filters, and filter factors.
REFERENCES
TM 11-401 and TM 11-401-2
Learning Event 1:
USE OF FILTERS
1.
Introduction. Copy photography requires special techniques not always used in other types of
photography. Besides a well-supported camera and flat field lens, you will require special film and a
complete understanding of black and white light filter functions. This subcourse will cover these areas.
a. A photographic filter is a piece of transparent-colored material. They are made in three
forms: glass, gelatin, or gelatin sandwiched between two pieces of glass covers. The color of a filter
determines the color of light permitted to pass through the filter to the film. There are also apparently
colorless filters which correct for ultraviolet light, and neutral density filters which regulate the intensity
of light. Every filter holds some unwanted light and allows a portion of light to pass through to the film.
b. To use filters effectively, a photographer must be familiar with the theory of filter operation.
Important aspects include the effect of filters in relation to the color of the objects being photographed,
the color of the light source, and the color sensitivity of photographic emulsions used.
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