as the convergence angle increased beyond 60°. This might be 
mainly due to the unfavorable angles at which the circular 
targets used in that test (gummed reinforcements) were photo- 
graphed and viewed. This situation led to a strong indication 
that the optimum angle of convergence, in that particular pro- 
ject, seems to be in the neighborhood of 609, with a B/D ratio 
of approximately 1:1. 
3.6. Further Studies 
  
In order to test the theoretical and experimental indica- 
tions of the preliminary investigations outlined in Section 
3.5., a new series of theoretical and experimental studies was 
conducted. The new investigations centered on the cases listed 
in Table IV, and were conducted twice, using two different 
observers, for checking purposes. 
The formulae used in the preliminary investigation (Karara, 
1966) were used in the 1967 studies. These formulae are listed 
below for the sake of convenience. Referring to Fig. 23, the 
standard deviation of the deduced object-space point coordinates 
are as follows: 
  
4 2 2 : : 
+ (sir PrcOSÉ a, + (sin q,sing, - cosq, cosp, )^ m. (10) 
m 
  
: 2 2 
+ Mns sin Bm) + (m C958, (11) 
  
2 ; x 2.2 
& Micose, coss, m, } + cosy sing + sing cosp.) iit (12) 
m