302.185
Figure 8-6.–Slide duplicating system.
Regardless of the equipment being used, your goals
for duplicating transparent originals should be to
duplicate, improve, or alter, as desired, the reproduction
of the original.
DUPLICATING 35mm COLOR SLIDES
To get additional copies of a color slide, you must
either make several exposures of the original scene or
make duplicates from the original slide. When the scene
cannot be re-photographed, the only alternative is to
make duplicates of the original slide.
Other than making a number of duplicate slides
from an original, you can use the duplicating process to
improve a photograph. The image can be made larger or
smaller, the composition can be changed through
cropping, the density of the duplicates can be changed
from the original, and with the use of filters, the color
of the reproductions can be changed.
In most Navy imaging facilities a camera designed
especially for copying slides is used (fig. 8-6). This
camera setup usually consists of a unit having a camera
body and lens, bellows extension, light source, a
copyboard, filter holders, and the necessary controls and
switches. When slides are copied with a slide
duplicating camera, the slide is transilluminated. This is
the most common method of copying slides.
Exposure
Whatever method you use to copy slides, you must
make exposure tests. The original slide you choose to
make the tests should have average density and
brightness and normal contrast. This slide should be
retained as a reference slide. A full-frame slide of a color
rendition chart (color checker) serves ideally as a
reference slide. A color rendition chart allows you to
visually or objectively compare a series of colors and
densities of the original reference slide against the slide
duplicate. To visually compare slides, you should use
transmitted light and color viewing filters to judge the
slides. The objective method is more accurate. A
densitometer is used in this method. A densitometer is
an electronic meter that measures the actual density of
black-and-white and color materials.
Kodak Ektachrome slide duplicating film is
recommended for slide duplication. This film is
manufactured to provide lower contrast, less filtration
with tungsten lighting, and it has good color
reproduction characteristics.
The data supplied with the slide duplicating film or
the Photo-Lab-Index provides information that you can
use as a starting point for exposure tests. However, you
should bracket the exposure at least one f/stop in
one-half f/stop intervals on each side of the basic
exposure.
Slide Handling
The original slide must be clean to produce
high-quality duplicate slides. The smallest piece of dust
or lint is magnified greatly when the slides are projected.
Never touch a slide with your fingers. Handle the slides
only by their mounts. Hold unmounted transparencies
only by the edges. Dust or lint should be removed with
low-pressure air or a camel-hair brush. If there are
fingerprints or oily smudges on the slide, you can
remove them with a soft, lint free pad or a piece of cotton
dampened with film cleaner.
Slides should be placed in the slide duplicator
base-side up. When you are duplicating the full frame
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