One way to run a quick test print to determine correct exposure is to make your first print using a simple acetate screen called a Kodak Projection Print Scale. Here's how it works;
The scale itself is a piece of transparent acetate on which is printed a circle measuring 4 inches in diameter. This circle consists of black dots of varying density that form a pattern similar to wedges in a round pie. To use the scale, you set up your enlarger to make a print in the normal manner. Set your filtration as you would in making a regular print, using a "starting" filter pack. In the dark, place the transparent acetate Kodak scale directly on top of the sheet of printing paper. Expose for 60 seconds. The area covered by the Kodak scale will be exposed through the dot matrix on that scale. Process the exposed sheet in the normal manner. Each wedge of dots will be exposed to a different degree of darkness.
You can use the NYI Color Printing Guide to help you decide which wedge is best exposed, as follows: On the Guide is a series of prints entitled, Exposure Comparison Series. Compare the wedges in your test print to the pictures in the Series, especially the picture marked "Correct Exposure." One wedge should appear to your eye to be properly exposed. On that wedge a number is printed. This number tells you how many seconds exposure is correct for that print. For example, if the number "12" appears in the properly-exposed wedge, then expose your next print (without the Kodak scale) for 12 seconds. You should get a perfectly exposed print on this second try, provided that you expose using the same filtration, same aperture, and same lens-to-easel distance.
Realize, of course, that the color will undoubtedly be off. All the Projection Print Scale does is help you quickly figure out exposure; you still have to determine correct filtration.
A valuable tool to help you determine both correct exposure and correct filtration is a device variously called a filtration calculator, a subtractive calculator, a filter finder, or some other similar name.
The theory of these calculators is rather simple. They contain an array of acetate squares, each containing a different amount of yellow, magenta, and cyan filtration. For example, the Beseler Universal Color Calculator contains 127 such cmm ■
squares. Thus, by making a single print of your slide or negative using the Beseler calculator, you produce, in effect, a test print showing the result of 127 different filter combinations, one of which should be the correct filtration. How do you decide which square has the correct filtration? By deciding which square in your test-print comes closest to having no color at all. In other words, you select the square which appears closest to being pure gray.
If you're confused or surprised by this, we don't blame you. At first glance, this is very strange. But if you understand your theory of color, you'll see why it works, as follows.
Color calculators make an assumption — namely, that the average scene you photograph will contain an "average mix" of all colors. In other words, there'll be some red, some blue, some yellow, some green, some purple, etc., with no single color predominating. This means that if you mix together all the colors that go to make up a print of that scene, you should produce in your print an equal amount of dye in all three layers of the print-paper —yellow dye, magenta dye, and cyan dye. Now, as you already learned, if you mix all three dyes equally, you get a neutral colorless tone — a gray tone.
To enable you to measure the "average mix" of color in the image projected by your negative or slide, you place a milky diffuser in the light path, so that all the calculator "sees" is a diffused mix of all the colors in the image. What you print in each of the 127 squares, therefore, is the "image" of diffused light that represents the average color-mix in the entire scene. Since each of the squares has a different amount of filtration, the square that produces the grayest — most colorless — image represents the correct filtration for the average colors in the negative or slide. Once you decide on which square is "grayest," you determine the filter pack needed to produce a good print by consulting reference-markers relating to that square. Then you make a regular print of your negative or slide using this suggested filtration, and you should obtain a good print.
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