(35) 
are permitted under conditions when no cloud shadows are cast upon the area 
to be photographed. Exposure is determined visually or by photo-electric means. 
Usual exposure is 1/200 of a second at f:7 or f:8. 
Italy 
Mounts for the Santoni and Zeiss cameras are adjustable for drift correction. 
They are supported on steel springs and rubber. The Nistri cameras use rubber 
as a support material. A nadir point registering device is used in the Nistri 
cameras. The EIRA* is studying a method of image-motion compensation by 
moving the lens. No camera port glass is used with any of the cameras. Most 
photography is done in clear weather but about 20% is carried out under some 
cloud. The poorest conditions used are 30% cloud. Exposure is determined 
empirically. Usual values are 1/150 to 1/200 of a second at from f:4- 5 to f:9. 
For some photography with the Santoni cameras, the sun and a watch are photo 
graphed by the solar periscope which is connected to the camera. A statos- 
cope may also be photographed. A photographic altitude of 4,000 metres (13,000 
ft.) is used extensively. Other altitudes used are lower than this and range down 
to 500 metres (1,600 ft.). 
Netherlands 
The mount for the RC-5 camera is of the circular cardanic (gimbal) type 
with shock mounting rubber AN8008-D15 as a support material. This material 
was selected by Corten 21 at KLM and built into the Wild camera after tests 
had shown that vibration was producing deterioration in some of the photo 
graphs obtained. The reconstructed mounting was completely satisfactory. The 
mean angular velocity in service is I o per second. The RC-5 is always flown 
with automatic pilot and tilt does not normally exceed I o . Photography of a 
vertical gyroscope is under study. 
The Williamson Ordnance Survey Camera is mounted in a circular cardanic 
(gimbal) mount on a rubber supporting material. The Zeiss P-10 is on steel 
springs. 
A camera port glass constructed and fluorided by Wild is used with the 
RC-5. With the Ordnance Survey Camera the yellow filter is used as a camera 
port glass. No camera port glass is used with the Zeiss P-10. 
Photography is normally done only in clear weather, tor some purposes a 
small percentage of clouds is permitted. Worst conditions encountered are 
haziness over tropical bush. Exposures are determined by experience according 
to geographical position, time of day, and altitude. Typical exposures for 
the RC-5 are 1/150 or 1/250 of a second at f :4 - 2 or sometimes f:8. For the OSC 
and the P-10 typical shutter speeds are 1/50 or 1/100 of a second. With the RC-5 
auxiliary cameras are used to photograph a statoscope and in Decca trials a 
Decometer. Altitudes used are 1,050 to 4,600 metres (3,400 to 15,000 ft.) with 
the RC-5, 4,800 metres (16,000 ft.) with the OSC, and 4,000 metres (13,000 ft.) 
with the P-10. With the RC-5 air temperature at the camera is controlled 
automatically at 21°C. 
*Ente Italiano Rivieli Aerofogrammetria (Italian Company for Photogrammetric Plotting).