6.
Adjusting Filter Packs for Changes in Paper Emulsions.
As with color paper for printing color negatives, when you use reversal
color papers with different emulsion numbers, an adjustment to the printing
standard filter pack must be made.
The package label of reversal color paper or the instruction sheet for the
paper gives the "filter correction" values for that particular emulsion
number. The filter corrections may contain both + and - values.
Filter calculations are made easier by converting all filters to their
equivalents in subtractive colors if they are not already of the subtractive
colors.
For example, 20R = 20M + 20Y.
Also, add filters of like colors
together in the calculations. For example, 10M + 20M = 30M.
Step 1.
Determine the basic filter pack by subtracting the filter
correction printed on the label for the old emulsion from the filter pack
used for that emulsion.
Example: Step 1. Suppose the filter pack required for the old emulsion was
10C + 05Y, and the filter correction printed on the package label of that
emulsion was +10C -25M -05Y. Set up these values as follows:
Filter pack used for the old emulsion: 10C 0M 05Y.
Subtract old emulsion filter correction: +10C -25M -05Y.
To simplify the subtraction of minus values, follow this rule: Change all
the signs of the values to be subtracted and proceed as in addition.
Therefore:
Step 2. Determine the filter pack required for the new emulsion by adding
the filter correction value printed on the label for the new emulsion to the
basic filter pack.
Example: Step 2.
Suppose the filter correction value of the new emulsion is
-05C +25M -20Y.
5-7
SS0514
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