CORRELATION OF CAMERA AND VIEWER/
Fig. 4-3. Camera focus
less than normal.Fig. 4-4. Viewing stereo-
gram made with camera
focus less than normal.basic diagrams with others showing the actual structure of the
image.
Fig. 4-5 is a key diagram to the series. The triangular object
A”B”C“ is seen by two eyes or, photographed by two lenses, at
EE’. Pn is the normal picture plane for the normal image A”B”C”.
Pd is the picture plane for the distorted image D”F”G”.
Rays A, B and C connect the eyepoint E with the three signifi-
cant points A”, B” and C” of the original object and also of the
orthostereoscopic image A”B”C”. The small circles indicate the
intersection of these rays with the plane Pn. Points D, F and G
are disposed in the same plane symmetrically to A-B-C.
If we assume the stereoscope to have lenses which are half the
focal length of those in the camera, we place the plane Pd half-
way between the plane Pn and the eye plane as shown. Then
from A, B, C, D, F and G perpendiculars are drawn from the
original Pn plane to the Pd plane, thus locating A’, B’, C’, D’, F’
and G’ in the latter. Because D, F and G exactly correspond to A,