LESSON 3
piece of photographic material with a series of exposures on it used to
evaluate the developer solution. (The evaluation and control of the
developer solution is only one of the many uses of the sensitometric strip.
The sensitometric strip is a very significant part of sensitometry; the
science of determining the photographic characteristics of light sensitive
materials.)
(6) If the composition of the developer is kept constant, the
information derived from the sensitometric strip will tell you graphically
that the contrast of the material you are processing is staying constant.
If replenishment is too great, or too little, a sensitometric strip will
indicate that the contrast (gamma) has increased or decreased.
4. Measurement of pH. In the laboratory, pH measurement is a matter of
great importance. There are hundreds of acids and alkalis (bases) of
varying strength (fig 32).
Figure 32. pH values of common substances
Practically, pH can be viewed as a measurement of the acidity, alkalinity,
or neutrality of a solution. The pH scale is shown in Figure 33.
Figure 33. pH values
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