If this is not the case, the light level must be adjusted. Remember that adjusting the light level also affects the visible/IR ratio. Also, increasing the lamp voltage causes the IR level to drop.

10. When the 100 cd/sq ft level is correct and the ratio acceptable, calibrate the remaining light levels as follows: slide the blade control all the way to the right and adjust the corresponding detent block on the front of the Light Source. Ignore the visible/IR ratio for the 800, 50 and 6.25 cd/sq ft positions.

Calibrating the Horn

This procedure involves measuring offset and gain.

1. Insert the Horn Extender Plug into the Horn Connector on the B-600 Electronics Unit front panel. Plug the Horn into the Extender Plug.

2. Connect a DVM across pins 9 and 14 of the Extender Plug (the two on the far right, one above the other).

3. Slide the Master Camera on the Horn with the shutter blades closed. The DVM should read less than 1 mv (0.001 volt).

4. If not, adjust the offset: insert a screwdriver in the hole on the right side of the Horn, toward the front of the Camera. Adjust the Offset control until the reading is less than 1 mv.

5. Open the shutter blades until they are at full aperture. Place the Horn and the Standard Camera in front of the Light Source set at 100 cd/sq ft.

6. The DVM reading should correspond to the number marked on the Master Camera.

7. If not, insert a screwdriver in the hole on the left side of the Horn, toward the front of the Camera. Adjust the Gain control until the voltage is correct.

1. Plug the calibrator into the Horn Connector.

2. Set the CAL/TEST Switch to CAL.

3. Set the two switches on the Calibrator in the AMB and CONT positions.

4. Starting with the 75 exp. range, set the Range Switch on the Electronics Unit and the rotary switch on the Calibrator to the positions shown on the label on the rear of the Calibrator. Do this for all ranges except Flash Timing.

5. For Flash Timing, set the Range and rotary switches to the proper positions.

6. Set the CAL/TEST switch to TEST.

7. Insert a fresh film pack with battery into the Master Camera.

8. Place the Strobe Detector over the strobe and charge the strobe by pressing the red Strobe Charge button.

9. Fire the strobe by pressing the flash button: the reading in stops error should correspond to the reading marked on the Calibrator label.

Checking Graywall Reflectance

1. With the Master Camera on the Horn, set the Motor Switch to OFF and the shutter blades at full travel.

2. Set the Electronics Unit to 640 FLASH EXP.

3. Place the Horn with the Master Camera 4.5 ft. (137 cm) from the graywall.

4. Charge the strobe and fire it with the flash button on the front of the strobe.

5. The reading on the STOPS ERROR Meter should correspond to the reading on the Master Camera.