of the THRESHER search yields some indication of the 

 progress made in the Intervening years. 



The Naval Reconnaissance and Technical Support Center 

 fitted approximately 925 of the THRESHER photographs into 

 a photo mosaic which includes most of the wreckage and the 

 surrounding area. It is too small to see much detail, so a por- 

 tion of It is shown in Figure 8. This portion, which contains 

 about 25 individual photographs, shows the sail, high pressure 

 air bottle, and other small debris. 



A similar mosaic was also made with the SCORPION photo- 

 graphs. The use of the wide angle cameras made it possible. 

 to obtain similar coverage with about 20^ of the number of 

 photographs needed for the THRESHER mosaic. This gain is 

 Illustrated by a comparison of Figure 9 with Figure 8. 

 Figure 9 is a single photograph of SCORPION'S sail. No 

 attempt has been made to use equal scales for the two fig- 

 ures, but the areas shown are certainly comparable and the 

 reduction in the number of required photographs is a 

 significant improvement in the search capability. On the 

 other hand, the THRESHER mosaic certainly contains more 

 detail than the SCORPION photograph. On a given film 

 size, a narrow angle lens will generally produce a more 

 detailed image than a wide angle lens. 



While the wide angle camera was an ideal search camera, 

 the standard model 204 cameras were used to obtain more 

 detailed photographs once the submarine had been located. 

 For this portion of the operation, three cameras were used 

 one wide angle camera and two standard units. One of the 

 narrow angle cameras was loaded with color film while the 

 other two cameras were loaded with black and white. The 

 color film really did not provide any additional Information. 

 With the "fish" 30 feet off the bottom, the light must travel 

 through a 60 foot water path. This long light path is a 

 narrow band blue filter. If blue photographs are desired, 

 better ones can be obtained by viewing black and white photo- 

 graphs through a blue filter. The black and white film is 

 less grainy than the blue layer of high-speed color film. 



A number of different films were used during the search. 

 Kodak Trl-X on a 4 mil. Estar base was used for the first 

 part of the search. This was later replaced by Kodak Lino- 

 graph Shellburst which has a number of advantages. Though 

 it is a bit slower, it has finer grain, higher resolution and 

 higher acutance. It is more readily available and is designed 

 for high temperature processing. The color film used was 

 Kodak Ektachrome EF, This film was returned to this country 

 for processing, but the black and white film was processed 



47 



