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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