CHAPTER XXVIII 

 GEOLOGIC PHOTOGRAPHY 



By Robert F. Collins 



Ability to photograph geologic phenomena clinically in the field is a rare and 

 valuable attribute. Equipment and procedure are simple and attainable by the 

 average amateur and when employed they assure superior results. For outdoor 

 work in geologic photography there are three axioms: 



1. Work in the field, not the darkroom. 



2. Stop down and use a tripod. 



3. Use a sunshade. 



The importance of following these three rules cannot be overemphasized; they hold 

 true regardless of the film, lens, and shutter used. 



Photographic Field Equipment.— Equipment for field photography must be 

 adequate and practical. Five items are fundamental and should be assembled in a 

 kit which can and will be carried by the owner in the field at all times: camera, tripod, 

 sunshade, exposure meter, and filter kit. Pictures are not obtained by equipment 

 left in the car. 



The camera may be of any sturdy type, not prefocused, equipped with an anastig- 

 mat lens. A focusing back is not essential and action shots are never taken; hence box 

 reflexes are unnecessary, and fast shutters a luxury. On the contrary, shutter speeds 

 from lio to 2 sec. are most useful. Size of negative today is not of prime importance, 

 anything from 35 mm. to 33^ by 43^ in. is satisfactory and practical. Larger cameras, 

 of course, yield very fine results, but their bulk and weight are entirely unnecessary; 

 the 5- by 7-in. ones are absurd for field photography. Fast lenses are not required, 

 except for some color work; an//7.7 or//6.3 is entirely adequate. The lens, however, 

 should be of the very best correction for flare, coma, and spherical and chromatic 

 aberration; the ultimate limit of needle-sharpness will naturally be determined by 

 lens refinement. Fortunately nearly all modern high-quality speed anastigmats are 

 satisfactory for field photography if stopped down. 



A tripod which will support the camera firmly is essential. Slightly oversize good- 

 quality telescoping metal tripods will usually hold the camera satisfactorily in various 

 wind conditions. Bulky and heavy tripods, in spite of their greater stability, are 

 impractical for the field geologist; they are too much to carry. A valuable procedure, 

 in addition to shortening the tripod legs when a field photograph must be taken in a 

 stiff breeze, is to suspend a 4- or 5-lb. rock close under the tripod head. Finally, use 

 the tripod on every shot, even if there is an //1. 5 lens on the camera. 



A sunshade should be used at all times. Direct sun rays are only one danger; 

 bright sky light, water surface reflections, and snow glare are others. Use a sunshade 

 for every exposure, and for piece of mind use a good one and a big one. 



A photoelectric exposure meter should be carried and used. In spite of the latitude 

 of modern film, an exposure that is correct pays dividends later. For color work, a 

 photoelectric meter is a necessity. 



Filters, selected according to the owner's experience, should be part of the field kit. 

 K2, K3, infrared, and panchromatic green should be ample for black-and-white work. 



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