Abstract
It is the purpose of this paper to examine what conditions or assumptions are necessary before photography can be used as a practical tool in craniology ; the error limits in photographic measurement are less than the-1 % that is considered permissible in direct manual measurement. Among the factors affecting photographic measurement, perspective distortion is selected for the purpose of this study. A theoretical formula of distortion is introduced. Experimental testing of this formula is carried out. After several checking procedures, the data obtained are finally compared with theoretically calculated values. In addition, an examination of 11 Japanese skulls is made comparing the photographic and direct manual measurements. The results of these examinations suggest that the theoretical approach and the procedure utilized in the experimental tests are satisfactory. The conditions is that when using a 35mm camera, acceptable craniological data will be obtained from photographs where the field angle of the lens is under 2 degrees, or where the focal length is over 800 mm.
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