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REPORT OF COMMISSION VII 61 
weapons. À camera with an open shutter, registers muzzle flashes and tracers 
absolutely and distinctly, and the light which is always in the sky, even on dark 
nights, is quite enough for the exposure of a sensitive film in about ten minutes 
or perhaps half-an-hour or more. In this way, the contours of the terrain appear 
in the photo; this facilitates the fixing of the positions of the sharply defined 
flashes and tracers in the film. Stereo-pairs are naturally desirable for photo- 
grammetric completion of imperfect tracers, etc. 
For fast reconnaissance with patrols behind the enemy lines, the camera 
material must be easy to handle and light to carry. Amateur cameras with good 
optics and only a few adjustments and a size of 21X31 in. (6X9 cm.) have 
proved to be most suitable. If the camera is larger, it is unwieldy; if smaller, 
the photos are too small and have to be enlarged. The focal length should be 
about 4" (10 cm.), which gives a photo 
scale of 1:5,000 at a distance of 548 
yds. (500 m.). This scale is generally 
sufficient to permit vehicles and guns 
to be identified without difficulty. Be- 
cause of the need for speed, the film 
ought to be developed as soon as the 
patrol has returned, preferably in a 
developing box with the possibility of 
daylight loading. The contents of the 
photo can usually be fixed immedi- 
ately through interpretation of the 
negative; this should be done by per- 
sonnel who are well acquainted with 
the organization and equipment of the 
enemy, and in the presence of the 
patrol leader and the photographer. 
Only in exceptional cases should it be 
necessary to make prints. 
A special camera should be men- 
tioned in this connection. This is the 
Land Polaroid camera or the so-called 
“One Minute Camera.” It produces a 
dry photo, ready for interpretation 
within one minute of the finishing of Fic. 1. Swedish built camera for ground 
the exposure. Thus, the observer can photo reconnaissance. This picture shows the 
  
: : camera mounted with photo and viewfinder 
immediately draw on the photo what- periscope (A and B respectively) for photography 
over the top of a trench. (Manufactured by Ross 
AB, Victor Hasselblad, Gothenburg.) 
ever observations have been made, 
and in this way complete his report 
  
  
   
with a record quickly-produced anno- 
tated photo. 
It can also be assumed that the principles of the "Land" camera can be 
used for other reconnaissance cameras, when quick results are necessary. 
When it is a question of detail-reconnaissance, the camera equipment must 
be absolutely first class. The cameras should have exchangeable optics consisting 
of a normal lens, with a focal length of about 6" (15 cm.) and teleoptics with 
focal lengths of up to about 40" or about 100 cm. The size of the photos should 
be not less than 22 X31 in. (6X9 cm.). The lenses must be of high quality and 
very well color-corrected. A night lens with a great relative aperture of at least 
f/2 and a focal length of 4-8 in. (10-20 cm.) should. be included in the lens 
equipment. The cameras must be well equipped with color filters and prepared