Calibrating The Auto Circuit; Auto Circuit Calibration Specifications - Vivitar 283 Service Manual

Aut omatic Electronic Flash
Model 283
4.2.9 CALIBRATING THE AUTO CI RCUIT
To check the auto circuit in the four automatic modes, set up the unit at a distance of 6 feet from the sensor
of a pulse photometer in an environment that is nonreflective except for the target. The target should have
a reflectance of 36% and measure a minimum of 4 by 4 feet. See that the unit is optically level with the tar-
get, flash it 5 times to assure full power in the main capacitor, and wait until the ready light starts to bl ink.
Set the calculator dial of the unit on ASA 25, and test the four color auto modes at the f-stops indicated on
the dial. All should test w ithin a tolerance of ±0.5EV.Test BLUE auto mode first, then RED , followed by
YELLOW. T his sequence should require the least amount of adjustment once the blue mode has been cali-
brated. Check PU RPLE mode last. It should fall within tolerance. The appropriate f-stops at ASA 25 and
the permissible upper and lower limits of the tolerance in f-stops and lux-seconds are as follows:
Table 4-2. A uto Circuit Calibration Specifications
BLUE f4.0
Variance from Spec. (EV) f-stop lux/sec
+0.5 = 4.75 =
173.0
0
=
4.0
= 123.0
-0.5
=
3.36
=
87.0
RED
f2.0
Variance from Spec. (EV)
f-stop
lux/sec
+0.5 = 2.38
= 43.5
0
=
2.0
= 30.8
- 0.5 = 1.68
=
21.7
YE LLOW f1 .4
Variance from Spec. (EV)
f-stop
lux/sec
+0.5 = 1.68
= approx. 21 .7
0
=
1.4
=
approx. 15.1
-0.5
= 1.18 =
approx. 10.6
PURPL E
f5.6
Variance from Spec. (EV) f -stop
lux/sec
+0.5 6.66
341 .0
0
5.6
241 .1
-0.5 4.71 170.5
Adjust the auto modes by turning pot R26 (at hole "F"). To lower lux/sec reading, turn counterclock-
wise, to raise, clockwise. (Fig. 4-1)
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Vlvlter 374 60598 (11 /80)
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