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SE € KEUFFEL 8 ESSER CC 
OPTICS ano METROLOGY DIV | HOBOKEN, N 
Fig. 31 - K € E Target 
3.9.2. Use of Micro Flat Glass Plates of 1/4 inch Thickness 
  
It seems logical to expect that the use of micro flat 
thick glass plates will lessen the irregularities casued by 
thin glass, which is regularly used in current stereometric 
cameras, 
3.9.3. Larger Scale of Photography 
  
It seems logical to expect that both the theoretically 
expected and the experimentally deduced precisions of stereo- 
metric systems will increase as the scale of photography (S in 
Fig. 12) is increased. One of the problems with most current 
stereometric cameras is that they have a fixed focus, and 
this, in turn, governs the minimum object distance. The 
University of Illinois is in the process of acquiring a pair 
of cameras suitable for object distances from 0.5 meters to 
some 100 meters. It is hoped that these new cameras will 
be the nucleus of a stereometric system capable of fully 
satisfying the accuracy requirements of experimental structural