[Fig. 402]
The camera is opened either at the point where the lights are housed or at the lens point, whichever is most effective. Then, opening the shutter, the operator moves the camera either toward or away from the finger or skin to the point where the ridge detail is sharpest in the ground glass. The camera is held firmly, the ground glass is removed, the film is inserted and the photograph taken.
With respect to exposure time, it is possible only to generalize and point out that each case will have its own individual aspects. Controlling features for consideration will be the type of film, the type and size of lights, the method of lighting (direct, side, transmitted or reflected) and also whether or not filters are used. Accordingly, there may be a wide variation of exposure time in different cases.
The best approach for arriving at the proper exposure time is merely to make a test exposure, develop the film, and from an examination determine if it is underexposed or overexposed. Time the next exposure accordingly, until satisfactory results are obtained.
As has been mentioned previously, when photographing the ridges on fingers or skin, the ridge detail will be in reverse position, the opposite from an inked impression made from the same skin or finger. (This is true except in those cases in which the underside of the epidermis is photographed.) Accordingly, when the negative is printed, it should be printed gloss side to sensitive side of paper to give the position comparable to an inked print made from the same skin or finger. In order to avoid error or confusion a notation should be made on the photograph of each finger, or, if they are cut and mounted on a fingerprint card, point out that the position has been reversed and that the prints are in their correct position for classifying and searching. Otherwise, it is possible that the right hand may be mistaken for the left hand and vice versa.
If the underside of the epidermis or outer skin is being photographed, the negative should be printed in the normal manner, that is, emulsion side of negative to sensitized side of paper. Here, reversal of position is not necessary for when the ridge detail is viewed from the underside it appears to be in the same position as the inked impression normally is reflected on a fingerprint card.
Care should be taken to see that each photograph is labeled correctly to indicate the finger it represents, such as right thumb, right index, right ring, etc. It is imperative that no error occurs in such labeling, inasmuch as it is highly probable that the resultant classification would be incorrect and failure to make an identification might very easily follow.
Deceased infants
The foregoing has dealt with the securing of fingerprints of unknown deceased persons for identification purposes. The basis for such action is the presumptive possibility that the unknowns had been fingerprinted previously and through this medium might be identified.