Quantum CALCU-LIGHT X Operating Instructions Manual - page 3
When the batteries are weak two dots appear above the digits in the Calcu-Light display when MEASURE is
pressed. When they first appear there is still enough power for many readings. When they appear before the digits
appear, the batteries must be changed.
To do so, remove the battery door by turning the battery door screw counterclockwise with a coin. Handle the new
batteries with tissue paper. Insert them and observe proper polarity. Replace the battery door and tighten the screw.
Press MEASURE. If the battery indicators appear, wipe the battery contacts with tissue paper to remove grease or
dirt. Occasionally, new batteries must be used for a short time before the indicators will turn off.
Cold temperatures will sometimes cause the battery voltage to drop and the indicators to turn on. That does not
mean, necessarily, that the batteries need to be replaced.
7. CALIBRATED MEASUREMENTS
The digital numbers displayed by Calcu-Light are calibrated illuminance values of lux or footcandles in the incident
mode. In the reflected mode they represent luminance values of candela per square meter (nits) or footlamberts. Use
the chart supplied for conversion.
When critical measurements of lux or footcandles are called for, use a DX-1 flat diffuser accessory. The dome
diffuser of the standard turret measures true illuminance for point sources only, but is superior for photographic
exposure measurements.
The readings obtained in the reflected mode are the average luminance values over the 30 degree measuring cone of
the standard turret. They are also correct values when using the SX-1 10° spot attachment, or the FOX-1 fiber optic
probe.
The accuracy of measurement is plus or minus one digit.
Digits Footcandles Footlamberts
1
.031
.045
2
.039
.056
3
.050
.071
4
.062
.089
5
.079
.11
6
.10
.14
7
.13
.18
8
.16
.23
9
.20
.28
10
.25
.36
11
.31
.45
12
.40
.57
13
.50
.72
14
.63
.90
15
.79
1.1
16
1.0
1.4
Digits Footcandles Footlamberts
17
1.3
1.8
18
1.6
2.3
19
2.0
2.9
20
2.5
3.6
21
3.2
4.5
22
4.0
5.7
23
5.0
7.2
24
6.3
9.1
25
8.0
11.5
26
10
14.4
27
13
18
28
16
23
29
20
29
30
25
36
31
32
46
32
40
58
Digits Footcandles Footlamberts
33
51
73
34
64
92
35
81
115
36
100
145
37
130
180
38
160
230
39
200
290
40
260
370
41
320
460
42
400
580
43
500
730
44
650
920
45
800
1150
46
1000
1450
47
1300
1850
48
1600
2300
Digits Footcandles Footlamberts
49
2000
2900
50
2600
3700
51
3300
4700
52
4100
5900
53
5200
7300
54
6500
9300
55
8200
11,700
56
10,300
14,800
57
13,000
18,600
58
16,000
23,500
59
20,000
29,500
60
26,000
37,000
61
33,000
47,000
62
41,000
59,000
63
52,000
74,000
64
66,000
94,000
Note:
Multiply footcandles by 10.8 to convert to lux.