Bruchlacher, Lofstrom, and Halonen, as well as the results achieved in 
practical applications in Finland, indicated great possibilities for the use of 
this auxiliary instrument in photogrammetrie mapping. Unfortunately, the 
horizon camera did not find much application outside of Finland and was almost 
forgotten by the end of the Second World War. 
In 1960, a new horizon camera, designed by Lofstrom and built by 
the Wild Company, became available. This camera photographs, by means of four 
separate objectives, the horizon in four directions (forward, aft, left, and 
right) on a 35-mm. film. An adjustable counter and a seconds clock are also 
photographed on the same negative. The focal length of each of the four 
objectives is approximately 32 mm.*, lens aperture f/5.6*, viewing angle 39°. 
There is no provision for changes of the lens aperture, or of the exposure time. 
The prototype of the horizon camera was equipped with three 
fiducial marks along the center line for each of the four horizon pictures. On 
the recommendation of the author, two fiducials were added in the latest models 
Principle of the Horizon Camera 
Fig. 1 
of the horizon camera. This allows the horizon to be measured in five 
locations. It also makes it possible to use the horizon pictures when one of 
the outside fiducials is obscured by portions of the aircraft radio or 
Aerodist antennas. 
The horizon camera rests in the same mount as the vertical aerial 
camera. Consequently both cameras are tipped and tilted simultaneously and by 
the same amount. A universal servo mount PAU-2 holds either an RC-8 or RC-9 
camera in addition to the horizon camera. A connecting rod between the 
vertical camera and the horizon camera is provided for simultaneous drift 
adjustment.