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Radiography in Modern Industry - Kodak

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Figure 49: Characteristic curves of two x-ray films exposed with lead foil screens. Circlednumerals <strong>in</strong> the figure correspond to the items <strong>in</strong> Example 2.Figure 50: Form of transparent overlay of proper dimensions for use with thecharacteristic curves <strong>in</strong> the solution of exposure problems. The use of the overlay andcurves is demonstrated below.Graphical Solutions To Sensitometric ProblemsMany of the problems <strong>in</strong> the forego<strong>in</strong>g section can be solved graphically. One method <strong>in</strong>volvesthe use of a transparent overlay (See Figure 50) superimposed on a characteristic curve. Anothermethod <strong>in</strong>volves the use of a nomogram-like chart <strong>in</strong> Figure 54. In general, the overlay methodrequires less arithmetic but more equipment than the nomogram method. The nomogram method<strong>Radiography</strong> <strong>in</strong> <strong>Modern</strong> <strong>Industry</strong> 73

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