710 



HANDBOOK OF PHOTOGRAPHY 



a. camera is suitable. The airplane should be chosen, however, with the foUowinp; 

 thoughts ill mind. It must have a suitable window which can be opened to permit 

 securing of the photograph without having any of the airplane structure, such as the 

 wing tip and the tail, show in the picture. The airplane should be one which can fly 

 reasonably slowly. The pilot and the photographer should be within speaking range 

 of each other, as the closest kind of cooperation is essential to success. 



The selection of an airplane for vertical photography is more complicated (Fig. 5). 

 In the first place, the airplane must have a floor structure through which an adequate 



Fig. 3. — Planimetric map which may be compiled from aerial photographs. 



camera hole and window for the pilot may be cut. The airplane should carry an 

 adequate gasoline supply and it should have sufficient horsepower to take its full load 

 of crew% photographic equipment, and gasoline to comparatively high altitudes. Most 

 vertical photography these days is being done at an elevation of about 15,000 ft. above 

 sea level, although it is frequently necessary for the airplane to go as high as 25,000 ft. 

 This airplane must be reasonably fast in order to combat the high wind velocities that 

 are often encountered at high altitudes. It must be reasonably free from vibration, 

 which might be imparted to the camera. Furthermore, it is desirable to select an 

 airplane affording the pilot maximum visibility, forward, dowm, and to the side. For 

 this reason, an airplane with a single seat in the pilot's compartment and a narro\\' 



