4. Look at those prints that are too contrasty with empty, glaring white areas.

5. When you compare the negatives of these prints with negatives from prints that have detailed and textured highlight areas, you will see that the overdeveloped negatives are too dense or opaque.

Overexposed or underdeveloped negatives are slightly more difficult to read, but the principle is the same.

The reason exposure and development affect the film in different ways is a function of the way film responds to different amounts of development. Figure 6 illustrates how this works.



10 MIN.

20 MIN.

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FIGURE 6 The effect of increased development on the shadow (S), middle (M), and highlight (H) densities of a negative.

FIGURE 6 The effect of increased development on the shadow (S), middle (M), and highlight (H) densities of a negative.

Imagine that Figure 6A is a negative developed for five minutes and being viewed edge-on with greatly exaggerated shadow, middle, and highlight densities. The diagonal line illustrates the negative's contrast. The steeper the line, the more contrasty the negative.

Figure 6B is the same negative after being developed for ten minutes. Figure 6C is the same negative after twenty minutes of development.

Notice that after five minutes' worth of development, all of the densities have reached a given level, and the contrast is relatively flat. After ten minutes, the density of the middle and highlight areas has increased greatly, but the shadows have hardly moved at all.

Develop for the Highlights 15

Because the middle and highlight densities increase at a much faster rate as the negative continues to develop, the overall contrast of the negative becomes much greater.

After twenty minutes of development, the highlights are much denser, but again, because the shadows have remained relatively stable, the contrast of the negative is increased.

This difference in the rate of density increase between the shadow and the highlight areas is a very convenient effect. If the shadow densities increased at the same rate as the highlights, the negative would simply become more dense without any increase in its overall contrast.

The point to remember is that increasing or decreasing the negative's development time doesn't affect the shadow densities nearly as much as it affects the highlights. This means that by varying the amount of time you develop the film, you can produce a usable negative regardless of how con-trasty or flat the subject of your photograph may be.

The general rules for controlling the contrast of negatives are as follows:

1. Your exposure should be based on the amount of detail you want to have in the darker areas of your finished print. Once the exposure is made, the shadow densities are established.


FIGURE 7 Shadow density is determined by exposure.

FIGURE 7 Shadow density is determined by exposure.

2. If the contrast of your subject is very flat, you can simply increase the negative's development time to make the highlight densities more dense and therefore the lighter areas of the resulting print whiter.

FIGURE 8 A longer development time increases the negative contrast of a flat subject.

3. If the subject is extremely contrasty (for example, dark foliage and bright snow in the same picture), you can compensate for this by giving the film less development.

FIGURE 9 A shorter development time decreases the negative contrast of contrasty subject.

In short, expose for the shadows and develop for the highlights.

To understand some of the implications of this rule, study the following discussion of development very carefully.

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