PROPOSED MODIFICATIONS OF CAMERA CALIBRATOR BASED ON EXPERIENCE GAINED FROM EVALUATION OF NAVY PROTOTYPE

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A000600050015-5
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 6
• Document Creation Date: December 28, 2016
• Document Release Date: March 21, 2001
• Sequence Number: 15
• Publication Date: September 1, 1959
• Content Type: REPORT

Approved For ReWse 2001/04/02 : CIA-RDP78B7A00060005 s-)
STATINTL
PROPOSED MODIFICATIONS OF CAMERA
CALIBRATOR BASED ON EXPERIENCE
GAINED FROM EVALUATION OF
NAVY PROTOTYPE
1, Neutral Density Filters and Zone Rheostats
Problem.,
The loss in illumination owing to the cos 4? law becomes appreciable for
the marginal area of cameras having large angles of view. The loss of light by
vignetting is in addition to that resulting from the cos 40 law. The loss in illu-
mination varies for cameras of different manufacture.
Solution:
It is recommended, therefore, that the bulk of the light loss owing to the
cos 40 law be balanced by the insertion of neutral density filters and any addi-
tional loss beyond the cos 40 law be balanced by varying the lamp illumination
through individual rheostats for each zone of collimators. Neutral density filters
are supplied i,a 0.1 density unit steps and shall be selected to compensate approxi-
mately the cos 40 law. The reason for balancing the cos 40 law with neutral
density filters is that the bulk of the correction is accomplished without a change
in color temperature and only a relatively small change in color temperature
results by use of a rheostat for a relatively slight change in illumination. The
majority of cameras to be calibrated will not be supplied with anti-vignetting
filters. However, when a camera to be calibrated is received with an anti-
vignetting filter, the neutral density filters can be removed and the illumination
balance achieved by rheostat adjustment. It is to be emphasized that the function
of balancing illumination is a problem owing to the variation in the cameras to be
calibrated and not the camera calibrator.
Declass Review by
NIMA/DOD
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Neutral density filters shall be installed as follows:
Zone
Densi
00
'... 0.6
7.5?
0.6
15?
0.6
22.5?
0.6
300
0.3
37.5?
0.3
450
None
The installation of 7 rheostats fulfills the requirement of individual zone
adjustment.
2. Trimming Rheostats
Problem:
Owing to the difference in the intensity of illumination between individual
lamps, the procedure in the past has been to select lamps of equal illumination.
A problem arises, however, when a lamp burns out. It is rather difficult to
insert a new lamp that is equal in intensity to the remaining lamps that have been
used for some time. The usual procedure is to replace all lamps when one lamp
burns out. This procedure is costly, time consuming, and requires a large stock
of balanced lamps.
Solution:
Install an easily accessible panel containing 25 trimming rheostats as a
means of adjusting the illumination intensity for over-all uniformity of each zone.
3. Rectification of resolution targets.
Problem:
Inasmuch as the reticle planes of all collimators, other than the central
collimator, are not parallel to the focal plane of the camera. the width of the radial
and tangential lines on the reticle are enlarged by a factor of cos 6 and cos 26,
respectively. on the calibration exposure. The current procedure to correct for
this effect, is to utilize specially prepared tables for each zone.
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Solution:
Prepare art work for each zone with the cos 0 and cos 28 effect compensated.
Prepare reticles from six different art work layouts. Since the cosines of 0' and
7.5?differ by less than 1 percent, the reticles of the 0? and 7.5? zone shall be
identical. Number the resolution targets consecutively for easy identification of
the 25 collimators.
4. Elimination of Electrical Console
Problem:
The electrical console presents no significant problem other than an acces-
sory piece of equipment connected to the camera calibrator by means of a electrical
cable. The basic reason for this design, was to isolate vibration.
Solution:
Redesign horizontal cross-section of camera calibrator from four semi-
circular recessed areas to one semi-circular recessed area and three straight
sides. This configuration results in greater "desk top" area and greater internal
space to accommodate electrical system and other storage. Constant voltage regu-
lator shall be mounted directly on the floor inside the camera calibrator housing but
totally isolated from the camera calibrator to preclude the transmission of vibrations.
5. Data Card Recording
Problem:
Lack of exposure number, make of camera, serial number, date, operator,
etc., on the calibration exposure as a permanent and integrated record.
Solution:
Installation of a data card projector for the recording of pertinent data on
the calibration exposure.
6. Other Modifications
a. One optical reflecting surface in lieu of two. Less light loss and easier
adjustment procedure.
b. Place center-annulus on resolution target; thereby eliminating the annulus
optical element.
c. Simplified x, y, z adjustment of collimator.
d. Simplification of camera holders.
STATINTL
1 September 1959
Approved For Release 2001/04/02 : CIA-RDP78BO4747A000600050015-5
 Approved For Release 2001/04/02 : CIA-RDP78BO4747A000600050015-5
STATINTL
Approved For Release 2001/04/02 : CIA-RDP78BO4747A000600050015-5
 Approved For Release 2001/04/02 : CIA-RDP78BO4747A000600050015-5
ILLUMINATION
CONTROL
TENSION
CONTROL
FIG 2. PRELIMINARY DRAWING OF
QUALITY EVALUATION VIEWER.
STATINTL
CROSS SLIDE
FIVE MOVEMENT
MACBETH DENSITOMETER
(NOT FURNISHED)
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 STATINTL
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