PREFACE

This data book has been prepared by the National Reconnaissance Office with the assistance of the National Photographic Interpretation Center to provide general technical information pertinent to the reduction of data obtained by the KH-4B camera system.

The KH-4B camera system is expected to be operational in the fall of 1967. This photographic system is a continuation of the KH-4 series with modifications to provide adjustable exposure control, selectable filters, and a change in the mechanism which provides image motion compensation as well as a 3 inch focal length terrain camera.

TABLE OF CONTENTS

INTRODUCTION
PANORAMIC CAMERAS
Panoramic Camera Data
Format Characteristics
Coverage
Camera Calibration
HORIZON CAMERAS
Horizon Camera Data
INDEX (TERRAIN) CAMERA
Index Camera Data
Titling Data
STELLAR CAMERA
Stellar Camera Data

INTRODUCTION

This data book incorporates the latest modication to die basic KHA camera system. The KH-4B camera system consists of 2 main panoramic cameras, a stellar/index camera and 4horizon cameras (Fig 1). The payload consists of 2 recoverable sub-systems, each containing approximately 16,000 ft of film (8,000 ft of film per camera). The 2 recoverable sub-systems are designated mission part 1 and mission part 2. The system may be used to meet either reconnaissance or cartographic objectives. lle camera (Fig 1) is oriented so that the forward camera in the vehicle is the aft looking, and the aft camera is the forward looking.

PANORAMIC CAMERAS

Each panoramic camera is mounted in the photographic vehicle at a 15 degree angle from the vertical, thus forming a 30 degree convergence angle. The cameras are designated as forwardlooking and aft-looking.

Panoramc Camera Data

Table 1. Panoramic Camera Data

LensPetzval f/3.5 T 3.8
Focal Length609.602mm (24.0 in)
Scan Angle70 deg +/- 35 deg from track)
Field of View5.12 deg (along track)
Usable Format29.323" X 2.147"
ShutterFocal Plane
Slit WidthsVariable-- from 0.17 in to 0.30 in
Film Load1. 70mm Wide
2. 8,000 ft per recovrable sub-system (part 1 or 2 of a mission) for each camera
3. 16,000 ft per recoverable sub-system
4. 16,000 ft per camera per mission
5. 32,000 ft total load for both cameras for a mission (part 1 and 2)
End Lap7.6&percent;
Image Motion Compensation (IMC)Camera nods proportional to velocity/height (V/H) ratio
Stereo Angle30.46 degrees
FilterVariable -2 position commandable
Film Type3404, Estar Base

Binary Values in Milliseconds

Least Significant Bit nearest the Takeup end of the format.1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
65536
131072
262144
524288
1048576
2097152
4194304
8388608
16777216
33554432
67108864
134217728
268435456
Most Significant Bit Nearest the Supply end of the format.268435456

Format Characteristics

Figure 2 is a complete record of the format for the forward looking and aft looking panoramic cameras. The following is a description of the various items on the film.

1. Camera Serial Number -- An imaged record of the camera manufacturer's serial number. An even number indicates the aft looking camera. An odd number indicates the forward looking camera.

2. Binary Time Word -- A recording of vehicle clock time to the nearest millisecond. The time word contains 29 bits plus a parity bit. There are six columns of 32 bits available, but only three columns of 30 binary bits are presently used as shown in Figure 3. The column nearest the film edge is column number one, and all 30 bits are illuminated to provide a registration for mechanical readout. Column two presents the time word in rows 1 through 29 with the 30th being the parity bit. Column three presents reciprocated time, again with the 30th bit being the parity bit. The data block is located outside the platen area on the taketip side. This me= that any time readout, as seen on the film, is associated with the following (next higher number) frame, or conversely, when ascertaining the time a particular frame was taken, it is necessary to look at the data block on the previous or lower numbered frame.

3. Titling Data -- The title is affixed crossway on the film between frames and consists of a pass number, frame number, an arrow (indicates frame to which title applies), mode (S for stereo, M for mono, or MS for mixed), date, mission number, camera (fwd or aft-looking), and classification. The letters D, A, and M, preceeding the pass number have the following meanings:

a. D The pass is descending from north to south.
b. A The paw is ascending from south to north.
c. M The pass is mixed; ascending and descending.

An E added to the end of a pass indicates an engineering operation

4. Panoramic Geometry Traces -- lines on either side of the format which aid in determining the locus of principal points of the lens.

5. A nod angle calibration system which, by means of a xenon flash triggered by an optical encoder mounted on the nod axis, images a series of small dots along the edge of the format.

6. Pan Geometry Fiducial Marks -- An image of the 73 holes through the film guide rails. Each hole is approximately 40 microns in diameter spaced at 1 centimeter intervals with a double hole at the center of format.

7. Time Track -- An image of a 200 cycle per second light pulse which records the camera lens scan rate.

8. Slur Time Pulse -- A stretched pulse which occurs immediately after the dock is interrogated in order to show the relation between the time marks and the clock time. This should permit the determination of the time at which a point on the format was exposed with accuracy of 2.5 milliseconds (3 sigma).

9. Start of Operation Indicator -- A cross imaged near the camera serial number on the last frame of the previous camera operation.

Table 2. Panoramic Camera Calibration

COMPONENTPARAMETERCALIBRATION
Main LensEquivalent Focal Length25 Microns
Main LensRadial Distortion1 Micron
Main LensConvergence60 ARC Seconds
Horizon OpticsEquivalent Focal Length25 Microns
Horizon OpticsPrincipal Point to Fiducial Intersection10 Microns
All LensAlignment Horizon to Pan and Pan to Pan60 ARC Seconds
Not dot encoderNod Angle positionOne dot every 19.78 arc sec of nod shat rotation

Coverage

Figure 4 shows the angles covered by the several cameras. Figure 5 shows the typical terrain coverage expected and lists the coverage for vanous altitudes. Figure 6 is a conversion chart to determine photographic scale at different distances from the format center over the altitude range from 80 to 120 nautical miles.

Camera Calibration

The panoramic camera lenses and horizon cameras are individually calibrated prior to being mounted on the panoramic camera. This individual calibration consists of determining the principal point of autocollimation and the equivalent focal length, and checking the lens distortion characteristics. Subsequent to this, each camera system is calibrated to determine the position of the horizontal cameras in relation to their respective panoramic camera lens. The accuracy of these calibrations is shown in Table 2.

HORIZON CAMERAS

Two horizon cameras are associated with each panoramic camera. The imagery from the horizon cameras is used to determine the attitude (pitch and roll) of the main panoramic cameras. The paired horizon cameras will operate simultaneously on altemate panoramic frames. The horizon camera formats are exposed adjacent to the main panoramic frames (Figure 2).

Horizon Camera Data

Table 3. Horizon Camera Data

Focal Length55mm
Depression Angle15 deg
FilterWratten 25 plus Commandable Attenuator
Exposure1/100 sec.
Film TypeSame as in main panoramic cameras
Angular Field of ViewApproximately 51 deg 44 min by 23 deg 28 min
Usable Format2.1X 0.9 in
Aperturef/6.8 or f/8.0 -- varies according to which cameras are primarily pointing toward or away from the sun

Panoramic Camera System Coverage

Altitude (n.m.)80859095100105110115120
Frame forward cover (n.m.)7.78.28.69.19.610.110.611.0011.5
Frame width cover (n.m.)117.0124.0131.0139.0146.0154.0161.0168.0176.0
Area pr. fr. (sq. n.m.x 10'28.910.011.312.513.915.316.818.420.0
Mission stero cover sq. n.m. x 10'64.95.66.27.07.78.59.310.211.1

Terrain Camera Coverage

A listing of the coverage and overlap of the terrain camra is shown below for selected altitudes between 80 n.m. and 120 n.m.

Altitude (n.m.)8090100110120
Side dimension of ground patttern (n.m.)120.6135.6150.7165.8180.8
Area coverage pr. fr. - sp. n.m. X 10'4(n.m.)1.451.842.272.753.27
Overlap - % 9.375 sec/cycle68.071.674.476.778.7
Mission stero cover sq. n.m. x 10'657.462.165.969.071.6

The horizon camera photographs have no specific scale associated with them, nor do they have an independent frame number. They arereferred to as the port or starboard exposures associated with the forward looking or aft looking panoramic camera frame. Port is defined as the left side of the vehicle as the observer faces in the direction of flight and starboard is the right side.

INDEX (TERRAIN) CAMERA

The index camera is a frame camera which provides vertical small-scale photography. It may be used for rapid correlation and indexing of main panoramic photography. The index camera also provides conjugate imagery for a relative orientation between the index and main panoramic cameras. This is necessary for eventual adjustment of attitude data (pitch, roll, and yaw) between the stellar and main panoramic cameras. The index camera is preset to operate at 9.375, 12.5, 15.625, or 18.75 seconds per cycle; based on the planned camera altitude, it can be programmed to operate independently from the panoramic cameras.

The terrain format is shown in Figure 7. Figure 8 shows the data block details and the start of operation marks.

>

Table 4. Index Camera Data

Lensf.4.5 T/6.75 AWAT
Focal Lengh3 Inches
Field Angle74 deg
Format Size4.5 by 4.5 inches
Film Type3401
Film Load 5 in by 2000 feet
Framesapprox 4800
ReseauGlass plate with 2.5 mm interval grid
FilterWratten 12
Shutter Speeds1/250, 1/500
Shutter TypeRotary, Efficiency 57¢
Overlap68 to 80 percent between 80-120 nm for 9.375 sec/cycle
Cycle Period9.375 sec/cycle
15.625 sec/cycle or
18.75 sec/cycle
Scale1/2,432,000 at 100 nm Altitude
Coverage22,700 sq/nm per frame at 100 nm altitude; 30x 10¹ sq /nm per mission

Titling Data

Present plans call for titling each frame sequentially from 1 thru n for any given pass. Frame count would then start at 1 for the first frame of the next pass. Mitling data would consist of mission number, pass number, frame number, date and classification.

The reseau grid forms a calibrated array of points on the photograph which may be used as an aid in correcting the eflects; of film shrinkage, lens distortion, and atmospheric refraction.

STELLAR CAMERA

Stellar photography provides a means forvery accurate determination of pitch, roll, and yaw during operational cycles. One stellar photograph is pointed out either side with the optical axis 10' above the horizontal. A reseau is provided to correct for image distortion and to recover geometric orientation.

Table 5. Stellar Camera Data

Focal Lengh3 Inches
Field AngleApproximately 23.5°
Format Size1.25 inch diamter with flats
Film Type3401
Film Load 35mm by 2000 feet
Framesapprox 16000
ReseauGlass plate with 2.5 mm interval grid
ShutterRotary
Knee Angle100°
Max Distortion15 microns (R) 5 microns (T)

Either of the stellar cameras can be capped if a light source (which could degrade the imagery from the other camera) shines directly into the lens.

The stellar camera cycle period is 3.125 seconds, while the terrain camera is operating in the dependent mode. When the terrain camera is operating independently, the stellar camera operates once for each terrain exposure. The lens serial number for each stellar camera is exposed on the format (see Figure 9). The time word is exposed adjacent to the port serial number. Ihe port serial number is further identified by a "P" after the number. Start of operation marks are exposed adjacent to the time word as shown in Figure 11.

Although the stellar imagery is originally produced on unperforated 35mrn film, it is customarily reproduced on 70 mm duplicate positives for case of handling by specified users as shown in Figure 9.

Present plans call for tiding each port and starboard frame sequentially from 1 thru n for each recoverable subsystem of a mission. Each port frame number is preceded by a P and each starboard frame number is preceded by a S. On the leader of the stellar film is a listing of the passes and their corresponding frames.