- 2 - 
b) Tangential distortion does not exceed 10 microns. 
c) Resolution using high-contrast, 3-line targets and photo 
graphing on Plus-X aerographic film produces an AWAR 
(area weighted average resolution as defined in MIL-STD- 
150A), ranging from 23 lines per millimeter to 33 lines per 
millimete r. 
d) The surface of the aluminum alloy magazine platen is plane 
within 0. 001". 
e) The between-lens Rapidyne shutter has speeds varying from 
1/10 to 1/500 seconds. 
f) The altimeter is rated at 50, 000 feet. 
When the KC-1 model was first introduced, the average values of 
radial distortion were reported and the fiducials were set to reference 
the Point of Symmetry as defined by Sewell. The Principal Point, as 
defined by Washer, was also reported. This was the KC-1 as it was 
developed 14 years ago. 
KC-1B 
In the last few years, the Air Force has updated the KC-1 with several 
modifications, giving it a KC-1B rating. The modifications are as 
follows: 
1) Hundreds of Planigon lenses have been reworked to reduce 
radial distortion to 10 microns or less. This has been 
accomplished by simply changing the thickness of the rear 
correcting parallel plate. The work was done by Fairchild 
in accordance with computations supplied by Goerz American 
Optical, the original lens manufacturer, based on photographic 
test data supplied by Fairchild and records of the individual 
lenses kept by Goerz. Values as low as six microns were 
obtained. 
2) Calibration now supplies more detailed data in accordance 
with modern needs. Distortion is reported for each quadrant 
along the diagonals of the format. The location of the Principal 
Point of Auto-collimation, Washer 1 s Principal Point, Sewell 1 s 
Point of Symmetry, and the distortion envelope is supplied. 
The use of Kodak's micro-flat spectroscopic plates, flat to 
20 x 10"^ inches/inch, guarantee more reliable and significant 
data than was obtainable when the KC-1 was developed (not 
considering data as obtained with Carman's interferometric 
method of flattening the emulsion surface of spectroscopic plates).