CAMERAS 



85 



field coincide. This scale is mounted in the window of the actuating cam so that 

 as the cam is rotated the scale rotates with it and a small index mark indicates the 

 distance between image and range finder. A small lens is placed so that the scale is 

 easily seen at one edge of the view. 



Mirror ^ 



Pivoi- 



^Mirror ^ 



Fig. 15. — Kodak pocket range finder. 



Kodak Coupled Range Finder. — Mechanically coupling the range finder to the lens 

 of a camera enables the user to measure distance and set the lens of his camera with 

 one motion. Thus the range finder becomes a focusing device rather than a distance 

 indicator, although it will also measure the distance of the object to be photographed. 



In the Kodak coupled range finder employed on certain miniature cameras, two 

 images of the same object are created by two lenses. To make the two images coin- 



F/e/c/ /ens 



Obj'ecfive 

 /ens L 



Divi'c/ing /ine-^^ 

 Ocu/ar /enses 



Field of view 



Objec/ive /ens M \ 



/mage formed by /ens L 



■Image formed by /ens M 



Fig. 16. — Kodak coupled range finder. 



cide, one lens is moved with respect to the other. The objective lens of the range 

 finder is carried on a movable support which is actuated by an adjusting cam which 

 is turned by the focusing knob. Turning this knob moves the camera objective along 

 its axis and thereby focuses it by means of a helical thread. This cam is so con- 

 structed that, when the range-finder objective is correctly placed for the given object, 

 the camera objective is focused upon this object. 



