Three-Dimensional Photography - Principles of Stereoscopy

CORRELATION OF CAMERA AND VIEWER 71

cent over normal. Figure 4-13 shows the result of viewing such a
stereogram. The object displays greater parallax and it appears
to be nearer the spectator than the original, but having the origi-
nal perspective it appears to be smaller than normal.
Figure 4-14 adapted from Luscher, illustrates graphically both
these base conditions. Assuming the use of the greater than nor-
mal base, L-L’ represent the two lenses, while E-E’ are the two
eyes. Note that for simplicity L’ and E’ are given the same posi-
tion. It would be equally correct to place E and E’ equidistant
from L and L’, but would involve a far more complex construc-
tion in the diagram.
In taking, the lenses form the image of triangle ABC from the

c

.-

Fig. 4-14. Fig. 4-15.