b. How to Use CC Filter. Let's look at an example of how to use them.
Suppose you decide that your test slide is too magenta.
(1) To verify this, you would view the transparency through a CC
filter that is complementary in color to magenta, which is green. Start out
by viewing the slide through a lower-density green filter, such as a CC 10
G, increasing viewing filter density until the slide looks corrected for
(2) Let's say that a 20 G filter corrects the slide.
You have a
choice of subtracting magenta or adding yellow and cyan filtration to the
If the trial filter pack does not contain any magenta, you
would have to add yellow and cyan filtration. Add equal amounts of cyan and
Eliminating Neutral Density.
Determining Minimum Number of Filters. Whenever neutral density is
in a filter pack, it adds unneeded density which increases exposure
Whenever you put a filter pack together, you should check it for
density and reduce the total number of filters in the pack to the
that will provide the correction that is needed.
(1) Suppose you needed to add 20Y and 20M to your filter pack and
this gave you the following:
(2) Neutral density is present in this filter pack because all three
subtractive primary colors (cyan, magenta, and yellow) are contained in the
To eliminate the neutral density, determine the largest number you
can subtract from each color. In this example, the number is 20. Subtract
20 from each color as in the following:
(3) Since the 2B filter is always used, we now have a filter pack of 2B
+ 110Y. Not only has the neutral density been removed, but the total number
of filters has been reduced. Whenever you reduce a filter pack, you will also
have to reduce exposure for the new pack. In this example, 20C and 20Y have