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New Zealand 
The camera mount used is of New Zealand design, constructed from steel 
tubing and supported on rubber Lord mounts. A camera port glass is used in the 
rear position in the aircraft. It is included in the calibration of the camera. 
Photography is normally done only in clear weather; the poorest conditions per 
missible are one-eighth cloud. Volcanic dust has been a considerable nuisance in 
New Zealand over recent years. Exposure is determined by means of an exposure 
meter fitted in the aircraft. Usual exposure is 1/200 of a second at f :5 - 6 to f:9. 
An auxiliary camera is used to photograph a Veeder counter, data card, a watch, 
and an altimeter. Photographic altitude is from 11,000 to 17,000 ft. 
Sweden 
A camera mount with adjustment for drift is supported on springs. No 
camera port glass is used. Photography is done only in clear weather except 
for a preliminary experiment under cloud. The poorest condition permitted is 
heavy haze. Typical exposures are 1/75 to 1/100 of a second at f :6 -3 or f:7. 
Normal photographic altitude is 3,900 metres (13,000 ft.). Instruments photo 
graphed by an auxiliary camera are a watch, an exposure counter, and a level. 
Switzerland 
A cardanic (gimbal) mount is used levelled on two axes by adjustment 
screws. The supporting material is rubber. A camera port glass is used with 
the Aviotar lens. This glass, which is considered as part of the optical system, 
has a diameter of 25 cm, a thickness of 24 mm, and is coated. Photography is 
done mostly in clear weather, with 5% being done under bright alto-stratus and 
strato-cumulus clouds. Exposure is determined by experience. Typical values 
are 1/150 and 1/250 of a second at f :5 • 6 to f :6 • 3. Photographic altitudes are 
from 500 metres to 4,000 metres above the ground. 
United States of America 
Most camera mounts are supported on rubber. The U.S.A.F. also use 
spring support. Their type A-28 mount supported on springs has dry friction 
damping amounting to approximately 0-7 of that required for critical damping. 
It is stabilized by servo systems controlled by a vertical gyro. Their mounts 
have natural frequencies of from 3 to 5 cycles per second. None of the civilian 
organizations reporting use camera port glasses, but the Air Force use them for all 
applications. Most photography for photogrammetric purposes is done only 
in clear weather. The poorest conditions under which photogrammetric photo 
graphy is carried out are under 10% of high cloud. The U.S. Coast and Geodetic 
Survey reports scene brightness ranges from 2:1 to 10:1 with brightnessess from 
50 to 300 candles per square foot. Exposures are determined by meter readings, 
by photographer’s judgment, or by both. The U.S. Coast and Geodetic Survey 
also use tables based on theoretical considerations and densitometer studies. 
Typical exposures range from 1/50 of a second to 1/200 of a second at f :16 to 
f:6-3. The U.S.A.F. use an auxiliary camera to photograph a Shoran record. 
The Coast and Geodetic Survey photograph a Wild statoscope. Photographic 
altitudes range from 6,000 ft. to 33,000 ft. The Air Force have provision for