800 HANDBOOK OF PHOTOGRAPHY 



Close-up Technique. — Geologic field photography is of two types: (1) close-ups to 

 show details of fossils, joints, and rock texture; and (2) land-surface views to record 

 a sweep of countr3^ Details of field procedure are given below: 



Close-ups are taken with tripod, sunshade, small stop, and panchromatic film, 

 usually at a distance of 6 ft. or less. Focusing should be done with a ground-glass 

 back, steel tape, or accurate range finder. Filters are rarely needed, and many times 

 orthochromatic film will be satisfactorj?-. 



Needle-sharpness and depth of focus are desiderata. Best results are obtained 

 by using a small stop and avoiding sunlit surfaces if possible. Apertures of //32 or 

 smaller are advisable except in a strong wind. Shadow contrast is usually desirable 

 only when illustrating surface texture of rock. 



Relative scale must be indicated b}^ including some readUy recognizable article in 

 the picture, such as hammer, knife, compass, watch, or coin. Do not depend upon 

 vegetation to give scale when photographing rock exposures close up; a clear record 

 of scale on the negative is superior to any statement in type. For scientific work, 

 people in geologic photographs are generally unsatisfactory and should not be used. 

 Human interest is not desired and is distracting, if only because clothing styles change 

 within the useful lifetime of a scientific negative. 



View Technique. — ^Land-surface views are scientific landscape photographs made to 

 record geologic features over large areas. They are among the most difficult negatives 

 that the geologist is required to make. The following points should be observed: 



Sharpness and clarity are of first importance. In spite of the temptation of a fast 

 lens and a distant view, always stop down and use tripod, sunshade, and exposure 

 meter. This procedure cannot be overemphasized. 



Filters should be used judiciously. If there is absolutelj^ no haze, a filter will not 

 improve the scientific value of the negative. Usually there is some haze in the dis- 

 tance, however, and filters should be selected according to the owner's experience. 

 The best technique for really distant views is infrared photograph}'-. Prints from 

 infrared negatives of distant topography are unequaled in sharpness and detail; the 

 false color values rendered are seldom of any hmdrance to the geologist. 



Correct perspective and advantageous viewpoint are essential. An assortment of 

 lenses, including a wide angle and telephoto, are valuable and usable additions to the 

 field geologist's photographic kit; unfortunately the investment is frequently pro- 

 hibitive. Telephoto lenses require exact focusing and absolutely rigid support, and 

 with most cameras such a lens calls for a heavier tripod than would be employed 

 otherwise. Excellent land-surface views are obtainable, however, with standard 

 lenses judiciously employed. 



Position of the camera and of the sun are important considerations in photo- 

 graphing distant geologic subjects. An elevated camera position is usually chosen, 

 if available, to minimize the immediate foreground and increase the field of view. 

 Shots against the sun are avoided, although much of the resulting flare effect can be 

 eliminated by the use of a polarizing screen. Shadow development should be con- 

 sidered where erosional forms are being photographed; registering the shadow relief 

 produced by a low-angled late-afternoon sun will mean the difference between success 

 and failure in many cases. Under noonday sun even areas of high relief usually 

 photograph with unwanted flatness. It should be noted that the desired type of 

 shadow contrast cannot be produced by darkroom manipulation; like portrait lighting, 

 it must be registered on the original negative. 



Although the scientist professes abhorrence of art in his publications, it behooves 

 the physiographic photographer to employ such artistic instincts as he may possess. 

 A strictly technical photograph of a land surface will be looked at and remembered 

 longer if its sky has clouds. Again, a pine bough framing an imused corner of the 



