The mo3t important quality of the subject photographed 
which determines exposures and development is its maximum 
and minimum brightness. We have a3 yet no instrument to 
measure these. In consequence usual procedures are based 
extensively on guess. 
Comm. 1. The Art of Taking and Examining Air Photographs 
J. A. EDEN 
Abstract 
The art of taking and examining air photographs has not 
kept pace with advances in cameras and emulsions and is 
responsible for very large and unnecessary losses of informa 
tion. The defects of present practice are examined. 
Various suggestions are made for improvement, and a plea is 
made for more intensive research into this important aspect. 
1. General Commission 1 has frequently discussed cameras and 
films, their various properties, and how to determine their 
characteristics, physical features, and image producing 
capabilities. As a result of these considerations, both in 
the Commission and outside, there have been enormous advances 
in instruments and materials. Our cameras now have wider 
fields of view, better shutters, larger apertures, better 
light transmission, less distortion and higher resolution 
than ever before. Films available now have greater speed, 
finer grain, better tonal rendering, increased stability and 
greater versatility. We may now. take photographs in black 
and white or in colour and it may be said that advances in 
these fields have been enormous and very worth while. 
1.1. It remains however that to obtain photographs and to 
inspect them in such a way that the finest details can be 
seen, one has to carry out certain procedures. The film 
must be exposed and processed, and prints must be made and 
examined. This I call "The Art of Taking and Examining Air 
Photographs' 1 , and this art, with some minor exceptions, has 
remained largely unchanged since air photography seriously 
commenced in the early 1920s. This state of affairs is not 
satisfactory. It is responsible for the fact that although 
it is now possible to obtain laboratory resolutions, 
enormously exceeding those possible in the early days of air 
photography, in practical work, the end product does not 
approach the improvement that might be expected from the 
enormous advances in instruments and materials. 
The rest of thi3 paper will deal with the art of taking 
photographs under three headings - The Negatives, The Prints, 
and The Examination. The defects of currently used 
procedures will be discussed, and various suggestions will 
be made for improvements. 
The Negatives 
2.1• Usual Methods of Exposing and Processing