384 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1936 



Salem, Mass. (pi. 2) which is claimed to be the first airplane photo- 

 graph to be used as a newspaper illustration. 



DEVELOPMENT OF THE AERIAL CAMERA 



Airplanes are supported by a stream of air passing by the air- 

 plane's wings, and as you sit in an open cockpit airplane in flight you 

 find yourself in a very strong wind due to the airplane's motion 

 through the air. This wind seriously interferes with the taking of 

 pictures and has led to the use of cabin airplanes for photographic 

 work, almost to the exclusion of the open cockpit type, and since sta- 

 bility and good visibility in all directions are desired for photography, 

 airplanes possessing these characteristics have been designed. Prob- 

 ably the best of these is the Fairchild monoplane knoAvn in the Army 

 astheC-8 (pi. 3, fig. 1). 



The rush of air and the vibration of the machine itself makes the 

 use of an ordinary camera for the taking of pictures from an air- 

 plane almost an impossibility. Even in the early airplanes, which 

 flew at speeds of approximately 40 miles per hour, the rush of air 

 was enough to collapse the camera bellows or carry them away, and 

 the flimsy construction of the camera allowed the lens to vibrate, 

 owing to wind or the vibration of the airplane, so that a sharp, clear 

 picture was rarely obtained. Early types of aerial cameras are shown 

 in plate 4. 



To overcome these difficulties cameras were designed especially for 

 aerial use. They are rigidly constructed fixed-focus cameras with 

 large lenses. Focal plane shutters were used at first, and the pictures 

 were taken on glass plates. The later aerial cameras have shutters 

 set between the lens elements. These have the advantage of expos- 

 ing the entire plate at the same time, thus reducing the distortion 

 in the picture due to the motion of the airplane during the time the 

 exposure is being made. Owing to its lighter weight, most aerial 

 cameras now use film instead of plates. 



Because of the limited angle of view which one lens will include 

 and the desirability of photographing large areas without an ex- 

 cessive amount of flying, multiple-lens cameras have been designed. 

 These include two-, three-, four-, five-, and nine-lens models. The 

 equipment necessary for printing these pictures is as elaborate as the 

 camera itself. The shutters of these multiple-lens cameras, which are 

 tripped either mechanically or electrically, must be carefully syn- 

 chronized so that they will all trip at the same instant. The five- 

 lens camera has an angle of view of approximately 140°, which 

 will photograph a strip of territory a little over five times as wide 

 as the altitude at which the airplane is flying. In flying at an alti- 

 tude of 25,000 feet photographs are obtained of a strip of land ap- 



