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(673) 
under fire, or in other dangerous situations. If the period for observation is 
short, the observer does not have time to fix the picture of what he sees on his 
brain, and later, to correctly describe what he saw. But, the camera can do this 
  
Fig.2. Look at the picture for half a minute. Can you then answer the 
following questions? 
How many objects are there? 
Is there an electric bulb among them? 
Was the padlock closed? 
Was the matchbox full of matches? 
Was there a bullet in the cartridge case? 
The camera remembers where the human mind fails! 
(see fig. 2), and no complicated photographic technique is necessary, on the con- 
trary, in this case the technique must be as simple as possible. 
If, however, one compares the ability of an undisturbed observer with field 
glasses to detect targets, with the corresponding possibilities of the camera, the 
comparison usually turns out to be to the observer's advantage. There are, how- 
ever, times when the camera sees better than the observer. When the distance 
haze limits the range of vision of the eye, and when the distance to the target is 
very great, the camera comes more and more into its own. Under such circum- 
stances, great focal lengths and infrared films provided with suitable filters, 
give results which can never be achieved by the eye. One can thus discriminate 
between two cases of photographic reconnaissance. The first, when the camera 
is used to register what the observer sees in a fairly short time, in which case 
simple, easily handled cameras must be used, and the second, when the whole 
scope of the technique of photography is used to discover things which the eye is 
unable to see. These two types of reconnaissance can be suitably called, “fast 
reconnaissance” and “detailed reconnaissance”. In both cases the photos must 
afterwards be submitted to accurate interpretation.