Quantum CALCU-LIGHT X Operating Instructions Manual

QUANTUM CALCU-LIGHT X

OPERATING INSTRUCTIONS

1. INTRODUCTION

This manual is yo ur guide to operating the Calcu-Light. Please read it
completely to fully benefit from the unique capabilities of your
instrument.

Refer to diagram 1 throughout this manual. There are two switch
controls, MEASURE and MEMORY. A LIGHT TURRET rotates to
enable either the incident or reflected light meas urement m ode. A
calculator dial provides f-stop, film speed, shutter speed, exposure value
(Ev) and cine (frames-per-second) values.

Diagram 1

2. SETTING FILM SPEED

First, rotate the outer dial rim until the reflected
window. This exposes the film speed dial, in the finger slot, on the right hand side of Calcu-Light.

Next, place your index finger into the slot and your thumb on the dial rim. Squeeze the rim and dial together and turn
them. The ASA and DIN numbers will change to the new values. If the desired value is not reached, reset the rim to
its original position, and again, rotate the rim and dial.

See specifications for the exact designations of film speed "dot" markings.

3. SETTING AND REMOVING LIGHT TURRETS

The standard Calcu-Light turret rotates to take either 30° reflected light or 180° incident light measurements. To
change the mode, l oosen the turret thumbscrew app roximately 4 or 5 turns . Lift and rotate the turret and tighten the
screw.

The selected mode is indicated by whichever turret symbol, reflected
of Calcu-Light. A mark on the instrument housing
light, the lens for reflected light.

The techniques of incident and reflected light measurements are covered in Section 5.

and incident symbols lie on either side of the digital di splay

or incident lies at the front (dial side)

serves as a reminder of the mode. The white dome for incident

To remove the turret turn the thumbscrew counterclockwise until it is free. Any of the accessory turrets described in
section 8 can now be mounted onto Calcu-Light.

4. TAKING A LIGHT MEASUREMENT
Point Calcu-Light in the desired direction and press the MEASURE control. A reading will appear in the display

window. Continue to hold the measure control to obtain updated readings.

Calcu-Light automatically remembers th e last light reading taken. To recal l this reading press the MEMORY
control. The digital light value indicated will not be changed by pressing MEMORY.

Set the digital reading obtained into the dial by turning th e dial rim. Use the incident

window or the reflected
window pointer corresponding to the mode se lected. The calculator dials should now show the correct combinations
of corresponding shutter speed, lens f-num bers, and cine (frames per second) values for the digital light value
indicated. Exposure values (Ev) also appear.

All line marking s on the dials are for one Ev, or stop, apart. Dot markings are 1/3 Ev incr ements, or 1/3 stop each.
The digital numbers of Calcu-Light are al so a sequence of 1/3 stop increments of light value.

Sections 7 and 10 give more detailed information about the digital and dial readouts.

5. EXPOSURE MEASUREMENT

Photographic light readings taken with Calcu-Light are categorized as reflected or incident light meas urements. The
system accessory attachments described in S ection 8 provide for special types of measurements within those two
categories.

Incident readings measure the light received by the subject from the (180°) hemisphere in front of the subject
(towards the camera). To take the reading, use the diffusing dome of the light turret by mounting it over the

mark
on the instrument. Hold Calcu-Light at the subject position and point the center of the diffusing dome towards the
camera position.

Be sure to avoid blocking any light sources. Take your reading and set the dials as previously described.

An incident reading is reliable and accurate because it is a measurement of light from its source, before it is reflected
and modified by the subject. The reading is not affected by the subject's color, tone or other reflectance qualities.
The resulting exposure places tones in the final picture (more or le ss) as they appear to the eye.

Reflected light readings, on the other hand, are essential for either convenience or special applications. They
measure light reflected by a subject in a specific direction. To take a reading use the lens of the turret by mounting it
over the

mark on the instrument. Point Calcu-Light towards the subject from the direction of the camera. You
may measure the subject up close or from far away, but do not block the light sources. Take your reading and set the
dials as previously described.

A reflected li gh t reading is calibrated to an average ton e, defined as 18% grey. A reflected reading of an 18% grey
card will result in the same exposure as an incident reading of the light source. And, the subject will be rendered as
18% grey in the final print.

A reflected r eading o f any s ubject results in an exposure that tends to render that subject as an "average" tone. That
is why reflected readings of predominately bright, or dark, subjects do not generally yield the best exposures. They
must be interpreted and modified. For general purposes inci dent readings are preferred.

Reflected light r eadings, however, are essential when the subject position is inaccessible for incident readi ngs, and
when the subject is itself a light source. They are useful for contrast and zone measurements to within 1/3 of a zone,
or stop.

6. BATTERIES

When the batteri es 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 repl aced .

7. CALIBRATED MEASUREMENTS

The digital numbers displayed by Calcu-Light are calibrated illuminance values of lu x or footcandles in the incident
mode. In the reflected mode they represent luminance values of candela per square meter (nits) or footlamberts. Us e
the chart supplied for conversion.

When critical measurements of lux or footcandles are called for, use a DX-1 flat diffu ser accessory. The dome
diffuser of the standard turret measures true illuminance for point sources only, but is superior for photographic
exposure measurements.

The readings o btained in the reflected mode are the average luminance values over the 30 degree m easuring 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 c o nv ert to lux.

Multi ply footlamberts by 3.48 to convert to candela/m2.

8. ACCESSORY ATTACHMENTS
SX-1 spot attachment

This attachment measures a 10° angle for reflected light, compared to 30° for the standard reflected mode. No
compensations are necessary. Use the reflected

window pointer of the dial.

CFX - 1 and 2 filter attachmen t s

These accessor ies provide for filtered light measurements. The filters supplied are standard photographic types.
CFX-1 contains the 80B, 85B, 25A, 8 and 4x (neutral density) filters. CFX-2 comes with the 81A, 82A, 11 and 21
filters. All common filter types are additionally available separately. CFX-1 is the basic set that contains a special
turret for mounting the filters.

Now when using a particular filter on a camera, the same type can b e moun ted on the meter. Filter factors, and their
variations due to color temperature of light sources can be dispensed with. Use the reflected

window pointer.

FOX-1 fiber optic probe

This accessory measures reflected light values of 1/8 inch (3mm) diameter areas on focusing screens, grou nd glass,
light tables and other luminant objects. It permits exact readings of scene contrast, and serves as a densitometer for
negatives and transparencies with a resolution of 0.1 density units. Use the reflected window

pointer. Additional

information is supplied in the FOX-1 instructions.

DX-1 flat diffuser

The purpose of the flat diffuser attachment is to make calibrated i llumance measurements and contrast
measurements with studio lighting. Its applications are better described in the CALIBRATED MEASUREMENTS
section.

Consult your photographic dealer for recent additions to the Calcu-Light/Calcu-Flash digital lig ht measurement
system.

9. PROBLEMS & SOLUTIONS

1. Digits only read 00.
Be sure nothing is blocking the light turret. Also, hold the MEASURE control long enough to obtain a reading.

2. Two readings of the same scene differ by one or two digits.
Usually, there is nothing wrong. Calcu-Light measures in precise 1/3 stop increments. Slight changes in position or
lighting are detected. If you measure fluorescent lighting you will detect the strobing effect, reminding you to shoot
slower than 1/125 second. Use the average of the highest and lowest reading.

3. Battery indicators appear momentarily after MEASURE control is released.
This simply indicates that the battery check circuits function. The batteries are good unless the indicators appear
while the MEASURE control is pressed.

4. Instrument shows no display.
Be sure the batteries are connected. Clean the contacts and springs if necessary.

10. SPECIFICATIONS
Intermediate Film Speed Markings

The DIN scale is marked in steps of 3 (0, 3, 6,...48). Intermediate markings (dots) are whole numbers, i.e., 0 1 2 3 4 5
6 ... etc.

The ASA scale shows only the bold type value s lis ted below. The intermediate values are marked by dots on the dial
scale.

0.8 1.0 1.2 1.6 2.0 2.4 3.0 4 5 6 8 10 12 16
20 25 32 40 50 64 80 100 125 160 200 250 320 400 500
640 800 1000 1200 1.6M 2000 2500 3.2M 4000 5000 6.4M
8000 10,000 12M 16,000 20,000 25M 32,000 40,000 50M

Ultra-High Film Speed Markings

Use the DIN scale pointer. There are four undesignated line markings to the left o f DIN 48. They are DIN 51, 54, 57,

60. These correspond, respectively, to ASA 100,000, 200,000, 400,000, and 800,000.

Ultra-Low Film Markings

Use the ASA scale pointer. There are four undesignated line markings to the right of ASA 0.8. They are ASA 0.4,

0.2, 0.1, 0.05. They correspond, respectively, to DIN -3, -6, -9, and -12.

F-Number Markings

The f # scale is marked with the bold type values below. The intermediate values correspond to the dots on the dial,
with the exception of f/0.7 and f/181, which correspond to lines. 0.7 0.8 0.9 1 1.1 1.3 1.4 1.6 1.8 2 2.2 2.5

2.8 3.2 3.6 4 4.5 5 5.6 6.4 7.1 8 9 10 11 13 14 16 18 20 22 25 29 32 36 40 45 51 57 64 72 81 91
102 114 128 144 161 181

Shutter Speed Scale

The shutter speed scale is marked with the bold type values below. Intermediate values correspond to dots on the
dial scale.

1/sec.

4000 3000 2500 2000 1600 1250 1000 800 640 500 400 300 250 200 160 125 100 80 60 50 40 30 25 20 15 12 10

Sec. 1/8 1/6 1/5 1/4 1/3 1/2.5 1/2 1/1.6 1/1.3 1 1.2 1.6 2 2.5 3 4 5 6 8 10 12 15 20 25 30 40 50

Min. 1 1.2 1.6 2 2.5 3 4 5 6 8 10 12 15 20 25 30 40 50 60

To obtain frames-per-second for m ov ie work, divide values in 1/sec chart by 2.

Contrast Ratio Table

The difference between two digital readings can be converted to the numerical contrast ratio in the chart below.

Digit difference con trast ratio

00

11.3:1

21.6:1
32:1

42.5:1

Digit difference contrast r ati o

16 40:1
17 50:1
18 64:1
19 80:1

20 100:1
53:1
64:1
75:1
86:1
98:1

21 128:1

22 160:1

23 200:1

24 260:1

25 320:1

10 10:1

26 400:1

11 13:1
12 16:1
13 20:1
14 25:1
15 32:1

27 500:1

28 650:1

29 800:1

30 1000:1

..

Model: Calcu-Light X
Capabilities: Incident, reflected, and calibrated light measurements.
Readout: Two digit L.E.D. display of light value in a 1/3 Ev sequence, 01 to 64.
Accuracy: 1/3 Ev.
Sensor: Blue enhanced silicon photodiode.
Me asuring Range: Ev -3 to Ev 21.3 for ASA 100 film.
Dial Markings: ASA 0.05 to 800,000

DIN -12 to 60
Shutter 1/4000 sec. to 1 hour
F# f / 0.7 to f / -181

Batteries: Mallory MS-76, 10L14, Ray-O-Vac RS-76, RW-82, Eveready 357, A-76, or equivalents.
Size: 10 x 7 x 3 cm. (4 x 2 3/4 x 1 1/8 inches)
Weight: 112 gms. (4 oz.)
Exposure Constants: (A.N.S.I standard 3.49-1971) k = 3.64; c = 25.6

A NOTE ON BATTERIES

To insure daily trouble-free performance of your meter, proper care must be given to the batteries and the battery
compartment.

1. Clean batteries - use clean tissue paper and rub gently. Handle batteries with tissue paper, not fingers, after
cleaning. When meter is left unused for extended period, remove batteries (do not stack).

2. Clean battery contacts use clean tissue pap er with alcohol, or pencil eraser. Clean all fou r contacts at the bottom
of the battery compartment.

3. Gently clean all four springs on the battery door.

The above procedures should also be followed before replacing old batteries with new ones and before you return
meter to factory for repair, or if batteries appear to be weak.