2 , 
DESCRIPTION OF CALIBRATION EQUIPMENT AND TECHNIQUES 
During the past several years, considerable work has been done 
to improve calibration techniques and equipment. Existing equipment 
has been improved in many ways. Mathematical equations have been 
perfected for calibrating the low-distortion lenses, particularly 
lenses for the Type KC-1 camera. 
FIELD CALIBRATION RANGE 
A number of improvements were made to the field calibration range 
shown in Figure 1, located at Wright-Patterson Air Force Base. A hori 
zontal camera mount was designed and installed in the camera calibration 
building. A device that would enable the camera's optical axis to be 
centered closely on the central target and the format diagonal to be 
aligned precisely with the line of targets was designed and constructed. 
Targets were repainted and light leaks eliminated from the calibration 
building. All targets were positioned with their center crosses on a 
geodetic level, and the angles between target centers were measured. 
The special glass-plate holder for the camera was reworked to prevent 
the plate from being bent during calibration. 
No action was taken to bring the vertical camera mount into use, 
which would provide further means for calibration. If the vertical 
mount is considered desirable, the target angles must be measured and 
the calibration results correlated with those of the horizontal camera 
station. 
COLLIMATING CALIBRATOR 
The collimating calibrator developed by the Perkin-Elmer Company 
is shown in Figure 2. Considerable difficulty has been experienced 
with this instrument from drift in the collimator tubes. The drift 
was caused by strains in the base positioning system and by vibrations 
from the light source transformers mounted on the rear of the collimator 
tubes. Considerable effort has been directed toward eliminating the 
drift, including installing large lock washers on the bolts of the col 
limator barrels and mounting them on the adjacent concrete base. Although 
these changes have reduced target displacements considerably, the instru 
ment still cannot be used for calibration unless the target angles are 
measured with the T-2 theodolite just prior to the calibration. 
Efforts are continuing to eliminate drift in this instrument. 
No results of its calibration have been correlated with calibrations 
by other devices as yet. 
GONIOMETER 
The goniometer shown in Figure 3 was procured from the Wild Instru 
ment Company. Early tests with this device produced results that were 
at some variance with calibrated focal lengths determined by the field 
range and the Fairchild multicollimator. As a result, use of this