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Enlarger and Easel Adjustments | Up
Photography (Basic) - Introduction to photography and other graphic techniques | Next
Figure 11-10.–Comparison of a number 0, 2, and 5 contrast printing filter |
the projected image on the focusing paper in the easel
and estimate the amount of exposure time you think the
print requires. From experience, you estimate the
correct exposure time to be about 15 seconds. Because
your estimate may be incorrect, a logical procedure is to
expose a test strip in four sections.
To make the actual test strip, you must do the
following:
1. Place one test strip on the easel in a position to
sample the highlights, midtones, and shadows.
2. Cover three quarters of the strip with opaque
paper or cardboard and expose the uncovered section for
5 seconds.
3. Move the cardboard to cover one half of the strip
and give another 5 seconds of exposure.
4. Again move the cardboard-this time to expose
three quarters of the strip-and provide 5 seconds of
exposure.
5. Now uncover the entire strip and expose it for
another 5 seconds. This produces a strip with exposures
of 5, 10, 15, and 20 seconds.
6. Process the test strip the same as contact prints.
7. Examine the processed test strip under white
light and select the segment representing the exposure
that gave the best results. If a time between two sections
gives the best result, make another test at the estimated
time. When you have selected the exposure, you are
ready to make a full-size print-if the contrast is correct.
If not, change filters and make another test strip.
The primary purpose for a test print is to determine
the correct exposure, but it can also help you determine
the correct contrast or printing filter to use. When the
test print is too contrasty or too flat, make another test
print with a higher or lower number of contrast printing
filter.
When printing, contrast (the difference in tonal
value between the highlights and shadows) is as
important for you to determine as is the correct
exposure. Almost all Navy imaging facilities use
variable contrast printing papers. To control contrast
with this type of paper, you must use variable contrast
printing filters.
Unlike film, increasing the development time of
paper does not increase the contrast significantly. In fact,
when paper development is carried out much beyond the
recommended time, contrast can actually decrease due
to fogging. Likewise, short development times should
not be used in an attempt to get lower contrast. The result
Table 11-2.–Multigrade Filter Selection Guide
Filter Number
Use
00
Normal prints from very contrasty
negatives. Produces very flat
prints from normal or low-contrast
negatives.
2
Normal prints from normal
negatives, flat prints from low-
contrast negatives, and contrasty
prints from contrasty negatives.
4
Normal prints from low-contrast
negatives, and contrasty prints
from normal or high-contrast
negatives.
5
Normal prints from very low-
contrast negatives, and very
contrasty prints from normal
negatives.
of short paper development times is usually a print that
is not fully developed, and the print has poor tone quality
and a “muddy” appearance.
Variable contrast printing filters are the only
practical way of altering print contrast with variable
contrast papers. Variable contrast papers have
orthochromatic sensitivity. The blue light-sensitive part
of the emulsion controls high contrast, and the green
light-sensitive part controls low contrast. By using the
proper variable contrast filter between the light source
and the paper, you can control the contrast. Variable
contrast filters range from yellow (low contrast) through
deep magenta (high contrast).
When making test strips to determine correct
exposure, you also need to determine the contrast. You
do this by examining the shadow area of the test strip
that has the correct highlight exposure. When the
shadow area of this test is too light, the test does not have
enough contrast. When the test does not have enough
contrast, a higher number filter is required. When the
shadow area is too dark, the test has too much contrast
and a lower number filter is required.
Table 11-2 is based on using Ilford Multigrade
filters and Ilford Multigrade papers. Ilford Multigrade
filters are available in the following 12 grades: 00, 0,
11-13
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