APPENDIX C 



and top. These were removed every time the camera was 

 taken out of the case, but they are now incorporated as 

 part of the brass box. 



Using the camera in the field resolved itself into 

 the following procedure. A reef having been found 

 where conditions such as adequate scenic effects and 

 sufficient numbers of fish could be found, the photographer 

 went down in his helmet and decided upon a suitable back- 

 ground or place to photograph. After choosing the spot he 

 measured off the distance to where the camera was to be 

 placed, appraised the amount of light, and ascended to the 

 surface. The camera was then loaded with film, wound up, 

 the lens set, because of the refraction of the water, to two- 

 thirds the distance measured below, and the diaphragm 

 adjusted to whatever aperture was considered necessary. 



The diaphragm setting employed during most of our 

 photography at depths of eight to fifteen feet, between 

 the hours of ten-thirty and one-thirty with bright sun as 

 near overhead as it could be, was between f. 5.3 and f. 8 

 using an f. 3.5 lens. Although we possessed a lens with an 

 aperture of f. 1.9 we found that fully exposed negatives 

 were obtained using the exposure mentioned. The speed 

 of the camera, of course, was standard, — sixteen exposures 

 a second. 



After the adjustments were made, the photographer 

 descended and the camera was lowered to him. He then 

 placed it on a tripod having a metal top, — the metal being 

 mostly to prevent the tripod floating away. The fish were 

 baited if it was necessary to concentrate them in one spot, 

 and the photographer pressed the lever whenever he decided 

 that the results would be worth while. The absence of 

 the slight vibration of the camera indicated when the 

 spring had run down and the camera had stopped. It 

 was then sent to the surface, rewound or new film inserted 

 if necessary, and again sent below. The camera contained 

 one hundred feet of film and ran for fifty feet on one winding. 



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