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lights” can easily jeopardize the results. Each camera should therefore be man-
ned, and its shutter closed, or the lens screened off when the battle-field is illu-
minated. If it is then necessary to take measurements on the photos, this can be
done with the usual stereoscopic methods. In most cases however, the positions
of the guns in action can be seen so clearly in relation to the terrain, that it is
not necessary to use special stereo-measuring methods in order to establish them.
A simple comparison with stereo pictures and the terrain, or with stereo pictures
taken in daylight, usually gives satisfactory intelligence.
In hazy weather, photographic observation of the battle-field sometimes
gives good results. The range of the camera with an infrared film and a dark
red filter or a black one, is then greater than that of the eye. The building of
fortifications, which, on account of the poor visibility is perhaps carried out
with less caution than usual, can then be detected.
Detailed reconnaissance photos are first interpreted by photo personnel
who usually have the greatest experience as to the way in which comparative
photo analysis is to be carried out, and of how infrared photos are to be inter-
preted. The results are, however, to be discussed with an officer who has first
class knowledge of the details of that sector of the front, after which the stereo
pictures are studied once more. During this second interpretation, fresh points
of view often crop up which had been passed over at the first one.
The results are then annotated on one or several prints, which are used as
key pictures. On the basis of these pictures, targets and changes which have been
detected are then marked in on maps and sketches of the enemy positions. In
broken up country, a panorama photograph with marked in enemy strong-
points, gives the most surveyable picture of the situation. These panoramas can
be made by the photo staff.
II. GROUND PHOTOGRAPHS FOR ACTION PLANNING.
Issuing Orders.
When issuing orders to subordinate units it is of great value to be able to
make the plan of action clear in a concrete way. Ground photos can often be
used for this purpose.
Enlargements of ground photos, taken from one and the same point, which
have been joined together to make panoramas, are the most suitable for use
when issuing orders. When it has been necessary to use separate camera stations,
the photos must be put together in such a way that their relation one to the
other 1s absolutely clear. Boundaries of sectors of the front and detected enemy
targets etc. must be annotated.
Sometimes, it may be advantageous to go through certain parts of the plan
of action with lantern slides (in exceptional cases in stereo), so that subordinate
commanders may follow the Commanding Officer's lecture without being dis-
tracted by distributed pictures.
Ground photos for order-issuing purposes can be made by means of the
photographic equipment which is available at that particular place and time. If
stereo pictures are to be taken, it is advantageous to use micro-cameras accommo-
dating a negative size of 24 X 36 mm which is best suited for standard pro-
jectors for stereo projection. It is to advantage to use colour slides when possible
to make them.
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