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HANDBOOK OF PHOTOGRAPHY 



of exposure to sunlight, the density of the negative is proportional to the area under 

 these curves, it is apparent that the panchromatic material is, in effect, considerably 

 more sensitive than the other two photographic materials. The peaks of sensitivity 



0.7 



0.6 



0.5 



o0.4 



« 0.3 

 I 0.2 



0.1 



300 



400 



700 



800 



500 600 



Wave length in m/i 



Fig. 11. — Relative sensitivity of panchromatic {A), orthochroinatic {B) and noncolor- 

 sensitive (C) photographic materials when used with sunlight illumination. These curves 

 are obtained by multiplying, wavelength by wavelength, the appropriate curves of Fig. 9 

 with the sunlight curve of Fig. 10. 



0.6 



0.5 



^0.4 



:Q3 



cO.2 



ZOO 



600 



400 500 



Wciveleng+h in m/x 



Fig. 12. — Relative-sensitivity curves for orthochromatic materials when used with 

 various light sources. These curves are obtained by multiplying, wavelength by wave- 

 length, the orthochromatic curve of Fig. 9 with the appropriate curves of the light sources 

 of Fig. 10. 



as shown in Fig. 9 do not vary by more than 20 per cent, but the relative photicity 

 as shown in Fig. 11 is about 1.00 for the orthonon material, as against 1.75 for the 

 orthochromatic and 4.92 for the panchromatic materials. The increased photicity 

 results from the fact that the orthochromatic and panchromatic films are sensitive to 

 a wider range of wavelengths than the orthonon or noncolor-sensitive films; to only a 



