64 REPORT OF COMMISSION VII 
miles (30,000 m.), but at a distance of 6.2 miles (10,000 m.) with a focal length 
of 39.4” (100 cm.). To make full use of the possibilities of the long lenses, one 
must place the cameras so high that the visual range does not fall below the 
optical range of the instrument. 
During a lecture at the World Congress at the Hague, in September 1948, 
I had the opportunity of showing a picture of a Swedish-built long distance mir- 
ror camera with as great an aperture as 30 cm. (see Figure 2) which was suitable 
for photographing at dusk. However, on account of air turbulence one cannot 
use such strong optics very often. The four element lens camera with a focal 
length of 98.5” (250 cm.) as shown in Figures 3-4 was therefore constructed on 
the basis of my experience and experiments with long distance cameras with 
  
  
  
FrG. 4 (a). The front part of the camera tube can be stuck into the back part for transport. 
(b) The 250 cm. camera folded for transport. Once folded, it can be carried by one man. 
various apertures. It has a considerably smaller aperture, f/15, and therefore 
takes less room and is not heavy to transport. The lens is designed for use mainly 
in the red and infrared parts of the spectrum. Very good results were achieved 
with the trial camera delivered in the summer of 1951, when photos were taken 
both in terrain and at sea, when turbulence in the air diffused the details in 
photos taken on the same occasion and with a great aperture. Examples of 
photography in terrain with this camera are shown in Figures 5-7, where the 
distance to the target was about 1 mile (about 1,600 m.). 
PHOTO-INTERPRETATION 
Photo-interpretation in military intelligence embraces interpretation and 
analysis of photographic intelligence material—aerial and ground photographs 
—in order to extract the greatest possible amount of intelligence concerning the 
enemy and the topography in general. Such activity may be said to correspond