(4
(4
2.3 ANOMALOUS COLOUR BALANCE ON TWO FRAMES
If the humidity in the aircraft is low as is often the case at
high altitude, film stationary in the exposure position or on the out-
side of the supply roll for any extended period. dries out and changes
its sensitometric characteristics. Two blank frames exposed before
starting a photo line, or the more extensive wind-over procedure recom-
mended for dimensional accuracy?, avoid the occurrence of anomalous
colour balance on frames in the photo line?.
2.4 CONDENSATION
Any condition that causes condensation on the film can lead to
turns sticking together and mechanical loss of image areas. Such a
condition can be any extreme temperature or humidity cycling. For
example, film in a magazine left in an aircraft overnight may encounter
very high humidities!.
2.5 PRESSURE MARKING
In shipping, excessive weight on the film container may bend it
and cause pressure on the film resulting in markings such as banding.
Stronger shipping containers would be desirable!.
2.6 CONDITIONING BEFORE PROCESSING
Film must be conditioned to room temperature in its sealed con-
tainer for 24 hours before processing. In practice this means that the
processing orgaization should condition the sealed film for 24 hours
in its laboratory before processing. Prior history of storage and
shipping conditions should be considered as unknown. !
3. STUDY OF EFFECTS OF ELEVATED TEMPERATURES
Subjection of aerial films to elevated temperatures should be
avoided as much as practicable. However there are many practical condi-
tions in aerial photography operations where avoidance of elevated
temperatures is difficult or impossible. It would seem useful to have
available some quantitative data on the sensitometric effects of ele-
vated temperatures on aerial films to permit discussions as to what
conditions can be tolerated and what must be avoided. Several
researchers*-” have reported variations in film properties caused by
heating, cooling, radiation or humidity but their results do not
provide data directly applicable to aerial photography.
