Some tests have been carried out to establish the displacements of the camera principal 
point with the variation of the lens position, 
Tables 3, 4, 5 show the results obtained through the tests carried out on three cameras. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Sm TEST 1 TEST 2 TEST à ne VEROPLAST apparatus 
Reading X Y X Y X Y X Y 13 x 18 f- 15 cm 
ex) 10/1: 41 -131+781-81+87]1-101+7 AEROGON lenses N? 00127 
28,2 -3]1]«7l]1e3l«13]1«41«8|71l]*9 
14,2 +91 + 4] + 824 3| +16 { + 5 +41 | +4 
9,5 = Sl 3 ANHIEB 
7,2 + 41-91 + 4 | -10 01-871 + 31-9 ^ 
5,8 |-122]-5] - s] -8] 41- s] - 9]- 6 y 
4,8 -7l1« 7T] -i3]I -* 1| -101]* 31] -10 | + 4 
48 [-12ls 9] <11} ‘ol olen] tos 1 zn 
5,8 -14l1- el - 91] -5] -101—8]| -111-. 6 id = 
7,2° 1 - 3/-5/-a}-11| 0 }—12|-21-5 i | X 
9,5 de 931- 3] +3l- 7) * 2|3 8] « 5| 7 $ \ | 
14,2 + TF+ a + 85T+ 5 + 61H 41 +61+14 Lee 2d 
28,2 ol. 31 -2]«121- 119 91] — 4] 410 — 
Oo 2121441 -13114-9]-51«21-9]-^5 
Table 3 
Focusing movement test : discrepancy of the principal point from the average position 
(values are in microns) 
Each camera underwent three sets of towards and backwards shifting of the lens among 
the positions corresponding to the focusing of objects placed between infinity and a distance of 
4.8 m. The discrepancies between the positions of the principal point corresponding to the same 
positions of the lens (column 2, 3, 4) are of very few microns : actually within the limits of the 
measurement accuracy. 
The average of the preceeding values is shown in the last column. 
The position of the principal point according to the variation of the distance of the lens 
from the focal plane are shown in the diagram : the straight line diagram shows the position of 
the principal point when the lens is taken away from the focal plane, the dashed line diagram 
gives the position of the principal point when the lens is approached to the focal plane. 
The examination of these two diagrams points out the following : 
1) the position of the principal point according to the different positions of the lens is the same 
both the lens is driven away from the focal plane and is approached to the focal plane. 
2) The principal point delineates a circle having radius lower than 0.02 mm around an average E. 
theoretical position according to the variations of the distance of the lens from the focal plane. eo 
According to our opinion the camera may be anyway used to survey close range objects 
for the following reasons : 
—50—