ASTRONOMICAL PHOTOGRAPHY 



745 



observed that the O emulsion is responsive to wavelengths between 2500 and 5000 A. 

 At the extreme upper right of the diagram the emulsion is particularly responsive to 

 wavelengths of 10,000 to 12,000 A. 



EASTMAN SPECTROSCOPIC PLATES 



I , 



■^/////////////A^^^^ 



SENSITIVITY 



HIGH 



HIGH 

 MEDIUM 



LOW 

 VERY LOW 



EMULSION TYPES AVAILABLE 



CONTRAST SENSITIZINOS RECOMMENDED 



MEDIUM ALL _ 



FAIRLY HIGH VISIBLE SPECTRUM t ULTRA VIOLET 



HIGH VISIBLE SPECTRUM & ULTRA VKJLET 



VERY HIGH VISIBLE SPECTRUM & ULTRA VIOLET 



VERY HIGH PANCHROMATIC ONLY 



144 HIGH IN INFRA-RED VERY HIGH PAN. & ESPECIALLY INFRA-RED 



-MATERIALS ARE DESIGNATED AS TYPE I-C, I-P. m-R. 144-M, etc.- 

 WHEN THE MAXIMUM SENSITIVITY IS REQUIRED 



THE SENSITIZING COVERING THE SHORTEST — 



SPECTRAL REGION SHOULD BE SELECTED. 



,AT X7600 m-K IS MORE SENSITIVE THAN m-N. 



X 3000 4000 5000 6000 7000 8000 9000 10000 1 1000 12000 



Fig. 4. — Sensitivity of Eastman materials for spectroscopic use. Black portions 

 show wavelengths for which plate is most sensitive. Shaded areas indicate wavelengths 

 of good sensitivity. 



Fig. 5. — Microdensitometer tracings showing the graininess of materials. 



The relative graininess of several standard plates manufactured by the Eastman 

 Kodak Co. may be illustrated from microphotometer tracings of regions which have 



