5 
Conclusions 
The writer has attempted to show that compared with 
what it could be, the amount of information obtained from 
air photographs is very small indeed, and that this arises 
from a lack of any rational approach to the problems of 
exposure, processing, printing and viewing. The losses 
are truly enormous. Large chunks of information may 
first of all fail to register on the negative itself. Of 
what is left, further large chunks fail to reproduce on 
the prints, and of what is reproduced on the prints, the 
resolution is degraded to two-thirds or a half of what it 
was on the negative. Even this is not the end of the 
deterioration because the reduced and degraded information 
remaining on the prints is examined by usual practice, at 
a magnification sufficient only to see the larger bits of 
it. 
One may well ask how it comes about that such a 
state of affairs could be allowed to prevail, and why it 
is that such seriously degraded photographs are accepted 
without complaint. The explanation of this as far as 
the negatives are concerned is that the user has no basis 
for comparison. He does not know what ought to appear 
on the negatives, and so has no grounds for complaint. 
With regard to the prints, here again the user will 
generally accept the prints he is given unless he has 
reasons to suppose they are seriously inadequate, and 
unfortunately he seldom compares them with the negatives. 
If comparisons between negatives and prints were more 
usual there would have been much less astonishment at the 
additional detail produced in the open fields by controlled 
dodging, because all this detail is to be found on the 
negative. 
These large information losses which occur in air 
photography very much reduce the economy of aerial survey 
procedures but it remains that the practical photogrammet- 
rist is mostly unaware of them. Being unaware of them he 
is untroubled by them, and so he gets ahead with his work 
as best he can. The writer has attempted to indicate a 
new and rational approach to what he has called the "Art 
of Taking Air Photographs", leaving many details remaining 
to be worked out. He believes however that further 
advances in these procedural processes promis e to be more 
rewarding than any other matters which are the concern of 
Commission I.