Pacemaker Crown or Speed Graphic.

by Jo Lommen


Top mounted  RF              Side mounted  RF      

Left: Top Mounted Graphic Rangefinder.                                    Right: Kalart Rangefinder and tubular viewfinder on top

In the late 1950's this top mounted range-finder with automatic parallax correction and interchangeable cams, appeared on the 4 x 5 inch camera only. Interchangeable cams were needed to calibrate the range-finder for different focal length of the lens.

The camera cost in 1958 - US $ 404,40 . At that time the average wages in USA were $  3673,80 per year !

Speed Graphic with Top Mounted Rangefinder

The principal feature of the new rangefinder is that it is instantly adaptable to any of the 9 standard lenses of different focal length. 

This is accomplished simply by changing a small cam at the time the lens is being changed. Each interchangeable cam is matched at the factory to the lens which it will be used and is designed to operate the rangefinder throughout the range of working distances for which the lens is intended. 

 

  

The right picture shows the ingenious tube with the plunger. On top of the tube the cam.

The P5 cam for use with 135 mm lens. Some other cams and their numbers:  P8 = 152 mm , P11= 162 mm,  P14= 90mm ,  P3=127mm ,    P25= 8 inch.

The cams are small, odd shaped metal plates that fit in a receptacle at the top of the camera house. 

They serve to operate the rangefinder  mirror by means of an arm which extends through the top of the camera. 

The motion of the lens track of the camera is transmitted to the cam through a row of metal steel balls encased in a tube; a small plunger enters the tube at the bed and pushes the entire row of balls through the tube. At the end of the tube, the last ball pushes another plunger thus activating the cam, which in turn operates the rangefinder mirror. In fact the tube filled with these small metal balls, takes the place of a complicated mechanical linkage which has always been through necessary previously. The simplicity of this new system containing no levers or connections to get out of order, adds a new degree of reliability to the rangefinder. Cams can be changed quickly and easily, without any tools. To exchange the cams please make yourself familiar with the working. The photos above show the way how to place the cam into the receptacle on top of the tube.

 

The earlier Crown with the side mounted Kalart Rangefinder as shown on the right picture and as described below.

The Pacemakers were the last Graphics made from 1947 to 1973 .

Two types were introduced. The Speed Graphic which has a Focal Plane Shutter and the Crown Graphic has only a front shutter. Both Speed and Crown were available in three sizes: 2 1/4 x 3 1/4,  31/4 x 4 1/4 and 4x5 inches. In 1949 the versatile Graflok back was made available on all Graphics.

Comparing to their predecessors, the light trapping of the lens standard and lens-board were of metal as was the back and the focusing hood. Striking are the hinged infinity stops, the new  focusing scale and a more solid wire sports-finder. Further more a tilt was added to the rising and shifting frond. The new built in shutter release was a very useful device enabling  to control the shutter without loosing grip of the camera house. 

 


 

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