566 



TABLE 



608.— SPECTRAL SENSITIVITY OF PHOTOGRAPHIC MATERIALS 



Spectral sensitivity is normally expressed in terms of the reciprocal of the energy 

 (ergs/cm 2 ) at various wavelengths required to produce a given density under given condi- 

 tions of development. The curves in figure 28 are shown for a scale of relative sensitivity 

 values, with a value of 10 assigned to the point of maximum sensitivity. The curves 

 should be regarded only as representative of the type of sensitizing for which they were 

 determined and are not suitable for quantitative use. In figure 29 spectral sensitivity data 

 are presented in a different form. Here the wavelengths to which classes of spectroscopic 

 plates are sensitive are shown in a block diagram. No indications are given of the way 

 in which sensitivity varies with wavelength. A solid portion of the block diagram indicates 

 the spectral region for which the class is especially valuable, i.e., where the sensitizing is 

 most effective. 



J 10 - 



Fig. 28, 



600 700 800 



WAVELENGTH IN MILLIMICRONS 



-Spectral sensitivity curves for typical films: 1, blue sensitive; 2, orthochromatic ; 

 3, panchromatic ; 4, infrared sensitive. 



7000 



8000 



9000 



3000 4000 5000 



V///////A TOTAL SENSITIVITY 



■■■■ SPECTRAL REGION FOR WHICH CLASS IS ESPECIALLY VALUABLE 



•CLASS REPRESENTS UNMODIFIED SPECTRAL SENSITIVITY OF SILVER HALIDE 



Fig. 29. — The range of spectral sensitivity of kodak spectroscopic plates. 



SMITHSONIAN PHYSICAL TABLES 



