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2. Environmental Conditions for Aerial Survey Cameras in Air- 
crafts 
Air pressure and temperature to which aerial survey cameras are 
exposed are to a high degree influenced by the type of aircraft 
and by the way the camera is installed, 
Reliable data are scarcely available. 
Therefore, the initiative Commission I - ISP took to gain 
statistical data is desirable and of great value. From the few 
material now available at Carl Zeiss, Oberkochen, two respect- 
ively three typical installations have been chosen and their 
impact has been investigated. 
2.1 Protected Installations 
Protection is afforded in this instance by a glass plate of good 
optical quality mounted in front of the camera and providing an 
air-tight seal for the cabin. According to information released 
by aircraft manufactures, cabin pressure is regulated at 600 torr 
for an altitude of approx. 6.500 ft and the temperature at 20°C. 
Even so, the electrical components in the camera, such as motors 
and illumination systems etc. generate a certain amount of 
natural heat. Their "body temperature" is therefore above the 
ambient temperature, at around 26°C in fact. Our environmental 
conditions are clear, then: outside the glass cover plate we 
have atmospheric pressure and temperature values that correspond 
to the external (standard) atmosphere; inside the cabin we have 
pressure of 600 torr and a temperature of 20° C. The camera's 
body temperature is 269 C. 
2.2 Unprotected Installations 
Here, the glass cover plate is dispensed with, leaving the camera 
exposed to the prevailing atmospheric pressure. With regard to 
the temperature, there are versions both with and without cabin 
heating. 
Where cabin heating is provided, only the foremost section of the 
camera, i. e. the filter(s), the front glass of the lens and 
certain parts of the body are exposed to the external temperature. 
The remainder of the camera body has a temperature somewhere in 
the-region of that prevailing inside the cabin. The sealing of 
the hole made in the fuselage to take the camera described under 
2.1 also contributes to the final temperature, which as numerous 
investigations have shown, averages out at 479C. 
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