GOOD DEFINITION 



ANGLE -^ - ANGLE 9 

 ANGLE-^ - 28.8° 

 ANGLEr, - 18.2° 

 ANGLEr,- 21.2 



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r 



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yWATER 



--Si?l£RA_ANGL^JJi3i!iS' 

 /S. 2r, -42.4° 



Figure 7. Optics for NEL Type III Deep-Sea Camera. 



The Kemlite flash tube and those of comparable design give ofF light of a 

 spectral quality approaching that of daylight. The short duration of the flash (1/1500 

 sec) will stop fast action and freeze normal camera movement. This results in pictures 

 of sharp definition. Also, light from the flash tube provides the duration and spectral 

 intensity required for color film.'"' The Heiland-Wilcox illumination is a repeating type 

 capable of being operated at 15-second intervals. Figure 4 shows in schematic form how 

 the electrical components are assembled to function with a 35-mm robot camera as a 

 compact unit. For faster repairs and exchange of parts and batteries, matched Jones 

 plugs have been utilized. To insure maximum light intensity, pictures are taken at not 

 less than 30-second intervals. The flash unit is operated on a set of two 2-volt Willard 

 wet cells wired In series. They can be recharged many times. 



Bottom Contact and Weight-Strength Relationships 

 Between Camera and Lowering Rope 



Positive contact with the bottom is essential to successful sea-floor photography. 

 Although there are various methods for obtaining contact, most are inefFective in depths 

 exceeding 1000 fathoms. A simple yet effective slack-wire technique employed at the 

 U.S. Navy Electronics Laboratory utilizes sensitive tensional changes in the 3/16-inch- 

 diameter wire lowering rope to detect the moment at which the camera reaches the 

 sea floor. 



