GOSSEN Luna-Pro F User manual

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                                                 Price $1.00
GOSSEN"
Luna-Pro F

Instruction
Manual

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Basic Operating Instructions
The following instructions are a quick operating
guide to the Luna-Pro F. For best results, also read l. b. Inserting & Changing the Battery
the additional sections describing in detail the dif- Your Luna-Pro F is supplied with a 9-volt batteryferent f unctions and applications of the Luna-Pro F. which fits into the battery compartment at the
bottom of the meter. Slide the battery compartment
l. a. Zeroing the Meter
With the battery removed, check to see that the
meter needle (3) rests on the green zero check point
(2). lf not, turn the zero adjusting screw (23) until the
needle rests on the zero mark.
lid (25) off and attach the battery to the battery ctip
inside. Note that the battery can only be connected
ca. Lux one way. Insert the battery into the battery com-
partment and slide the lid back on. Check the
mit Diffusor battery by pushing and releasing the power switch
bei 18 BIN (4) and then pushing in and holding the battery test button (16). The meter needle should be well within,
or to the right of, the battery test zone (12).
r 0 r zr 1g .r..t..1..t..1 l..l-.t..t tffi? ovER l:>

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l. c. Setting the Film Speed                                     l. d. Exposure Factor Scale
Determine the ASA speed   f rom the data supplied by        Check to make sure that the exposure   f actor scale
the  f ilm manufacturer. Rotate the clear  f ilm soeed         index mark (21)is at 1. A more detailed explanation
setting disc (.18) by the raised bars until the ASA          of this usef ul scale is on page '10.
speed number is opposite the white ASA index
triangle (B) A detailed ASA  f ilm speed table is on
page 40.





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l. e. Type of Reading l. f. Modewww.butkus.usof Measurement
Select the method of measurement desired, either Select the mode of measurement desired, eitherreflected or incident. (For details on incident vs. flash or daylight (ambient light). For daytightreflected measurements, see section ll. f.). For measurement, the red mode selector (7) should be
reflected readings slide the spherical diffuser (1)to in the depressed position; for flash measurement
the mode selector should be in the raised position.
Depress and release the mode selector to change
the mode of measurement (i.e., from flash to am-
bient). There is a graphic illustration on the side of
the meter which shows the positioning of the mode
selector necessary to take f lash or ambient
readings.
Note: The flash mode can be used for taking inci-
dent or reflected readings.
either side of the meter. For incident readings, slide
the spherical diff user in front of the measuring cell
window (22) until it "snaps" into the detent. l. g. Taking a Measurement
Follow Basic Operating Instructions steps l. a. thru
t. f.
For daylight measurement, mode selector (ll
should be in the depressed position (see Section l.
f.). Alm the meter at the subject for a reflected tight
r_eading or at the camera for an incident reading.
Depress and release the power switch (4). Rotate
the computer dial (11) until the meter needle is over

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the "0" null line. Read the desired combination of mains for convenient and repeated reference. For
f/stop and shutter speed on the computer scales. continuous measurements, see Section ll. a.
For f lash measurement, mode selector (7) should be
in the raised position (see Section l. f.). Aim the l. h. Reading the Scales
meter as indicated above. Depress and release the The Luna-Pro F has seven scales to give you infor-power switch (4). Fire the flash. Rotate the com- cine shutter speed, aperture, mation on ASA,puter dial until the meter nulls. lt is important to (EF) factor value (EV), exposure exposure speed,note that the red zero mark on the exposure correc-
tion dial should remain between the two red and Zone System values.
triangles on the meter face when nulling. lf the zero The time, or shutter speed, scale is calibrated frommark goes beyond either of the red triangles, the 1/4000 of a second to 8 hours and indicates valuesflash intensity is beyond the range of the meter.
When past the right triangle, the light level is too as follows:
low. When past the left triangle, the light level is too Hours are indicated 8h, 4h, etc.high. Minutes are indicated 30m. 15m. etc.
Read the proper f/stop oppositq the red flash in- Seconds are indicated 30, 15, etc. Fractional seconds are indicated,'2,'4, etc.dicator on the computer dial. This indicator is
located between the 1 and 2 second exposure Note that each section is alternately colored from
marks. the adjacent sections for ease of reading. The
indicates the proper reading point when red 1NOTE: When you release the power switch, the using'the flash measurement mode.value measured at that moment will be auto-
matically read, and electronically stored by the The ASA scale is calibrated in standard ASA valuesLuna-Pro F. To conserve battery life, the meter from 0.8 to 100,000 (100K). Intermediate values areswitches itself off automatically after 30 seconds. shown by short lines. A complete table listing theseand your measurement set on the computer dial re-

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intermediate values in on page 40. The cine scale allows direct reading of apertures
for various cine speeds (frames per second). These
CAUTION: Because of the extreme measuring speeds correspond to actual exposure times on the
possible F Luna-Pro it isrange of the -levelsundercom-ex- exposuredard shuttertimeangles.scale onlyFor XLforcamerascamerasorhavingthose stan-with very light high of conditionsceptional
ASA index high with a verybined
puter exposure- thattimethe scalecom- of the ends both displays
(8h and 1/4000 sec.). When this occurs, the COR'
RECT reading will be the UPPER part ofgthe scales!

EXAMPLES:
ASA 25,000 at HIGHEST LIGHT LEVEL:
Scales show above 1/4000 sec. at f/'128
but also (below) B hours at f/5.6 etc.
Obviously, HIGH ASA and HIGH light level add up
to SHORT exposure - 1/4000 sec. at ll',28.
The aperture or f/stop scale is calibrated trom f 1128
to f/0.7. Numerical values are shown on the scale at
full f/stoo increments. Intermediate values are in-
dicated by short lines at 1/3 stop increments. A
table of intermediate values and the mathematical
formula for calculating f/stops are given in Section
ilt.

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adjustable shutter angles, consult the camera's in- EV intervals. Exposure values are used elsewhere
struction book for the equivalent shutter speeds on several scales which will be explained later. lt is
and read your exposure opposite that speed on the important to remember that a change of 1 EV is
time scale. Also note that some reflex viewing equivalent to a change of 1 f/stop.
movie cameras use beam splitters to provide a light
path to the viewing screen. These beam splitters 'An EF (exposure factor) scale is included for mak-
reduce the light intensity to the f ilm plane, so that a ing exposure corrections when using f ilters,
correction factor must be applied to the indicated bellows, extension tubes, etc. lt is calibrated for ex-
f/stop. Once determined, the correction can be pro- posure factors up to 64. Detailed information on
grammed into the exposure correction dial. this scale is in Section ll.. c. The zone system scale
provides you with the tapacity to rdad lighting
An EV (exposure value) scale (19) is provided for ranges (in zone system values I thru lX) directly
cameras with shutters calibrated in EV. The Luna- from the computer dial of the meter. Further infor-
Pro F EV scale is calibrated from -8 to +24. mation on zone systems can be found in Section ll.
Numerical values are shown for full EV values with k.
intermediate values indicated by short lines at 1/3

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meter will now respond to all changes in light readings. This method has been incorporated into
values. For long term measurements, the ON/OFF your Luna-Pro F for maximum accuracy and ease of
switch has a lock position which.is indicated by the reading.
round switch position indicator (C). To activate and
lock the meter on: The basic operating difference between the Luna-
Pro F and a conventional meter is that, instead of
1) Depress and hold the power switch in. using various points along a complete scale length,
only one position (the null point) is used for all
2) Rotate the switch button clockwise until the readings and at all light levels. This results in
index mark is aligned opposite the round switch greater accuracy and ease of operation. There is no
position indicator. need to change scale ranges or to read different
scales. When the needle is set at the null point, the
The meter will now remain on for constant readings computer instantly shows a complete read-out of
until the switch button is rotated counterclockwise the measurement.
opposite the square position indicator where the
read and hold mode will go into operation for one To expand the capabilities of the Luna-Pro F
minute, after which the meter will again turn itself further, its meter face is also calibrated in 1/3 EV in-
off. crements from the null position to -r 3 EV for use in
scene brightness measurements, zone system ap-
NOTE: Be sure to return the switch button to the plications and lighting ratio measurements. Addi-
read and hold position (square mark) after using. tional information on this extremely useful feature
Failure to do so will result in short battery life. will be found in Section ll. i.
lf the meter needle is placed in "over" or "under"
ll. b. The Null Method of Measurement range, the readings on the calculator dial will result
in over or underexposure by the value indicated,
Laboratory instruments have long used the null compared to a standard exposure. method of measurement for obtaining precise
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Each numerically indicated major division on the The exposure correction dial is calibrated to work
meter face equals one EV (a change of one EV both in EV (exposure value) and EF (exposure fac-
equals a change by one f/stop or one shutter speed tor). Two index marks are provided at the center or
setting); the small intermediate dots are equal to normal positions for each correction method. In ad-
1/3 EV. dition, the red exposure correction signal (17) gives
a visual indication any time the exposure correction
dial is in use.
ll. c. Exposure Correction Dial
To use the exposure correction feature, determineOccasionally, the indicated exposure readings ob- the correction factor desired, in either EV or EF, andtained with any light meter must be modified for rotate the exposure correction dial while holdingbest results. This is especially true when using the computer ring stationary until the white indexfilters or when taking close-up pictures where the mark is opposite the correction value desired. Anylonger lens to film distance results in reduced light readings now taken will reflect this correction.at the film plane. To correct for these effects, com'
monly called filter factor and bellows (extension)
factor, additional exposure must be given to the
film. In addition, you may, for various creative
reasons, wish to depart f rom the standard exposure
values. For these situations, the Luna-Pro F with its
exposure correction dial, is ideal.
Normally when making exposure corrections, the
correction factor must be calculated and applied ffieach time a reading is taken. However, with the
Luna-Pro F the exposure change can be programm- S W11o-tl. SYSTEMed into the exposure correction dial. Any readings GossEN
will then be automatically corrected. www.butkus.us

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For example, assume that a filter with a filter factor photographic reading or by use of an accessory
of 4x is being used. This represents a change of 2 snap-on footcandle scale.
stops. By moving the index mark of the EF ring to a
position opposite the number 4, the meter readings A conversion table of EV to footcandle readings is
will automatically be compensated for the 2 stop included on the underside of the meter. To deter-
difference. mine the equivalent footcandle reading, set the
ASA f ilm speed scale to 50, slide the spherical dif-
Rotating the exposure correction dial corrects the fuser over the cell window for incident readings,
indicated exposure by changing the shutter speed point the meter toward the light source, and take an
(and flash symbol), cine speed, and EV scales. EV reading (null the meter). Turn the meter over and
Therefore, this feature can be used for still read the footcandle value opposite the EV reading be photography using available light and artificial just obtained. Similarly, lux values can also
light including flash, motion picture photography, determined. Note that for each change of one EV,
and with cameras calibrated only in EV. the footcandle level changes by a factor of 2. This is because the EV scale is equivalent to a full stop
After completing "corrected" measurements, be scale in that each change of one EV or one f/stop
sure to return the correction dial to its "0" posi- results in either twice or half the amount of light. A tion (red signal will be covered by black tab). for mula suitable for calculating intermediate values of footcandles is given in Section lll along
with pre-calculated values at 1/3 EV.
ll. d. Footcandle Readings
With The Luna-Pro F The most precise footcandle readings are obtained by means of a flat diffuser. When using the
The Luna-Pro F is a precision instrument designed spherical diffuser of the Luna-Pro F, all the light
to give highly accurate photometric readings falling on the diffuser from an angle of approx-
specified in readily usable photographic terms. imately 180" is integrated for a final reading. Since
However, footcandle readings can also be obtained most photographic subjects are three dimensional,
with the Luna-Pro F either by converting the this results in more accurate photographic ex-
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posures, but can give improper f ootcandle
readings. To insert the meter, open the case by unsnapping
When using the spherical dif f user, footcandle the fastener at the rear of the case and swing the
readings are most accurate when reading direct top section forward. Insert the meter strap through the openings at the rear of the case. Place the light beams such as from spots, arc lights, etc. meter into the bottom section of the case and
secure with the retaining strap. To remove the top
ll. e. Carrying Case section of the case completely, unsnap the
fastener at the bottom of the case.Your Luna-Pro F is supplied with an exceptionally
strong and functional carrying case. lt is con-
structed finest heavy-duty materials of the for long ll. f. Methods of Measurement protectionlife and extra Extra for the meter. thick
material and heavy stitching make this case There are two basic methods of obtaining measure-
suitable for the abuse encountered in professional ments with the Luna-Pro F, incident and reflected
usage. The complete top section of the case is light readings. Both methods are popular and when
removable for ease of handling when taking fre- used properly, both are valid and will give good
quent exposure readings. results. However, to evaluate properly the ways in
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which these two methods function, it is necessary Although it is not necessary to use such a curve to
to discuss briefly how the meter operates and how determine exposures, using one as an illustration
f ilm responds to light. lt is beyond the scope of this will help in evaluating proper light measuring
manual to get into a detailed discussion of sen- techniques. A representative sample H & D curve
sitometry, the study of tone reproduction. There are for a film is illustrated below.
many excellent books available on the subject,
2.00 some of which are listed in the appendix. This
manual will just relate in simple terms, how the 1.60
Luna-Pro F works and under which conditions you
may wish to use either incident or reflected light >'1.20
readings. troz
All films have characteristic responses to light H80
which, although they may vary from f ilm to film and
with changes in storage and processing, are
relatively predictable. This consistency of response 0.30 0.60 0.90 1 20 1.50 1.80 2.10 2.40
is what allows the use of light meters and other RELATIVE LOG E
photographic instruments to predict the final out-
come of an exposure. This curve shows, among other things, the change
of density of the film vs. the zog of the exposure.
Film responds to only a limited range of illumina- With negative film, as the exposure increases, the
tion levels before its ability to record that light il- negative density increases. lt is broken down into
lumination level properly is lost. Any instrument three distinct regions, the toe, straight line portion,
designed to measure or expose f ilm must take that and shoulder. In order to record detail properly on
into consideration. The response of the f ilm to light film, the light values (log exposure) should fall
is generally graphically illustrated by what is called within the range where they intersect the straight
a "characteristic curve" or H & D curve, named for line portion of the curve. lf the exposure falls into
Hurter and Driff ield who originated its use. the area of the toe or shoulder. the film will lose
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f ilm the same as a dark object with a highshadow or highlight detail respectively. This is record on
because, once those areas are reached, little or no level of illumination. To standardize these varying
change in f ilm density occurs with a change in ex- conditions and to allow you to work with different
posure, and it is the change of density that pro- meters and films, a reflectance of 187o value andduces differentiation and detail. Therefore, your the understanding that it represents a "typical
light meter must give you an exposure value that average" is the basis for readings taken with both
will adjust the measured light so that when it reflected and incident methods of measurement.
reaches the film, it will fall within the straight line However, under the same lighting conditions, dif-
portion of the f ilm's recording ability. ferent readings for the same scene can be obtained
when using both methods, depending on subject
The H & D curve shown above indicates relative log ref lectivity. This may seem strange at first, but it is
exposure. However, because different films have true, and sometimes causes conf usion. To
different light sensitivity ranges, which would af' eliminate this confusion (something no meter or
fect the density vs. log exposure in actual use, the other device can do), you must consider your sub-
meter must be programmed for these differences. ject matter and how you want it to appear on the
The ASA f ilm speed setting control on the f ilm. For simplicity, the discussion of ths evaluation
calculator dial of the meter accomplishes this pro- method will be broken down into a discussion of in-
gramming. cident and reflected light measurements.
In order for this ASA value to be meaningful, all
meters and other light measuring devices that ll. g. Incident Measurementrelate to photographic applications must take into
account not only the f ilm speed, but also the ref lec' When reading incident light, the spherical diffuser
tivity of the object being photographed. This is is placed in front of the measuring cell window and
because the film does not know what the ref lectivi- pointed toward the camera, i.e. opposite the sub-
ty of a particular object is. lt only responds to light ject being photographed, so that the diffuser will
levels. Therefore, all other conditions being equal, a receive the same light intensity and distribution as
light subject with a low level of illumination may that falling on the subject. The reading at this point
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indicates the strength of the light, but does not in- Situations may arise where you have extremes of
dicate the light value reflected from the subject into light and dark subjects, all of which are important
the camera lens and onto the film. lt does not in- in the same scene. Under these conditions, the
dicate the light value that would be reflected into meter should be used in the reflected light method
the lens from an 18o/o average reflective subject. as described under scene brightness range and
Therefore, when working with subjects that are zone systems.
primarily very light or very dark, the incident ex-
posure reading indicated should be adjusted to Incident light readings are most valuable when
compensate for the difference in reflectivity from determining exposures where the subject is inac-
the 18% standard. When the subject is very light, cessible and receives the same illumination as the
decrease the exposure by 112 to 1 f/stop. When the meter. They also allow you to determine the in-
subject is very dark, increase the exposure by 112to dividual strengths of multiple light sources striking
1 stop. The amount of change to the exposure will one subject by reading each source independently.
depend on your judgement as to the degree of varia- ln most cases with average subject matter, the inci-
tion in subject reflectivity from an average scene dent method is a fast, simple and accurate way to
(18% reflectivity). determine exposure.
(4. ll. h. Reflected Measurement
I\ I'\ When reading reflected light, the meter is pointed
a \t a toward the subject f rom the camera position
t Y t ,t without the spherical diffuser (1) over the measur-
reflected from the subject passes *rtF \ ing cell. Light through a collecting lens onto the measuring cell.
This is the same type of path the light takes when T/ z -/ exposing film in your camera. The meter cannot "read" any single element in its field, such as a
-/t' face or highlight; it integrates all the light reflected
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throughout the measuring field, and indicates an        main subjects of interest or one of the accessory
exposure which will record the total picture on the         spot attachments used to eliminate the effect of
basis of an overall 18% value                            the light or dark areas. As an alternative, an inci-
                                                         dent reading can be taken.
In most cases, you can simply use this reading to
get a perfectly exposed picture. However, there are       When measuring a subject that departs significant-
a few situations where the readings should be             ly from an 18% reflective surface, you may wish tomodif ied.                                              modify your readings. This is because the reading                                                               indicated will make the subject appear on the film
The Luna-Pro F has a measuring angle of 30" when        as if it were 18% reflective.
taking a ref lected reading. The light  f rom all objects
within that 30 o measuring range will be averaged to           In certain cases, you may not want the subject be-
give you the  f inal reading.  lf you have one or more          ing measured to fall into that category. For exam'                                                                                           cameraobjects that are significantly lighter or darker than          ple, if a reflected reading is set in your
the rest of the scene, the objects will bias the       when measuring a brilliant white bridal gown, the                                                                                                                                                                                                                                                     f ilm will appearreading away from the average. In cases such as          resulting image of the gown on the                                                                                                                                                         in-this. the meter should be moved in closer to the         with the same density as if it were 18% gray                                                         stead of white. Here again, you may wish to use an
                                                       incident reading or compensate the ref lected
                                                       reading by increasing exposure. The same is true
                                                                            for very dark objects,  i.e., a black tuxedo, except the
                                                      exposure would be decreased.
                                                                 Ref lected readings are particularly useful when try-
                                                               ing to evaluate the relative range of ref lected light
                                               from various subjects that may have different
                                                                                       ref lectivity and may be receiving different amounts
                                                      of light. Because the reflected reading measures
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With transparencies, about 1 EV is the largest prac- ll. j. Lighting Ratiostical shift if your main subject is close to 18o/o
ref lectance. Lighting ratios, the relative strengths of different
lights in a scene, can be used to create certain ISituations may arise where the meter shows a moods or effects. Sometimes, manipulation ofrange of light intensity that is beyond the total lighting ratios is needed to hold detail in shadow Irange of film acceptance. In these cases, the use of and highlight areas.
f ill light to lighten shadows or a "gobo" (a device to I
block or modify light such as a dark card)to soften To determine a lighting ratio, take an incidenthighlights may be indicated. When the proper cor- reading of the main light and null the meter. Then,
rective action is taken, the scene brightness range without readjusting the computer dial, read the can agai n be other light or lights in the scene. When reading the
checked to be sure secondary lights, def lection of the meter needle will the limits of the indicate the strengths of those lights in relation to f ilm are not ex- the main light. The method of reading lighting
ceeded. Modifying ratios is similar to that described under Scene the lighting can Brightness Range. also be used in-
stead of shifting
the exposure as
mentioned above ll. k. Fill Flash + if so desired, as in I the case of trans- When lighting ratios are very high, the difference of parency film the light levels in the areas of direct light and
where the main shadow may be so great that the film will not be
subject is close to able to record detail in both areas at the same time. 18o/o ref lectance lf this occurs, a useful technique for bringing
www.butkus.us such as with some lighting ratios to a more manageable level is fill
skin tones. f lash.

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By using supplemental flash, generally electronic 4) Since you want the shadow area to be 2 stops
f lash, a suff icient level of light can be introduced in- under the mid-tone, sel the f lash mark (5) at f5.6 (2
to the shadow areas to make proper recording stops under f.1.1).
ofdetail possible. The Luna-Pro F is a usef ul tool in
determining the relative strengths of available light 5) Take a reading (with the Luna-Pro F in the f lash
and f lash illuminating the scene and can help to ad- mode) with the flash unit directed toward the
I just to the proper lighting ratios. shadow area.
6) Manipulate the f lash unit (changing the position
or power control) until the meter needle deflects to
the null point. Make sure that little, if any, ambient Example Method l: light strikes te measuring cell of the meter.
Assume you are shooting a scene where, in order to
hold detail in a shadow area, you want the shadow lf you have a leaf shutter camera and are not able to
exposure to be 2 stops under the mid-tone reading. adjust the flash, you cari determine fill flash
exposure by adjusting the aperture and shutter
1) Take an incident reading and null the meter. speed settings.
2) Without moving the computer dial, read in the
shadow area. The needle deflection indicates theI shadow is 3 stops under your mid-tone (incident) Example Method ll:
I reading. lf you wish, electronic f lash can be used to Follow steps 1 to 3 as indicated for Method l.
bring more light into the shadow area and bring the
I shadow illumination into the desired range. 4) Fire the flash into the shadow area and take a reading with the Luna-Pro F in the flash mode. Let
3) Select your working aperture and shutter speed us assume that the f lash is not powerf ul enough to
from the initial incident reading (i.e.; at 1/125th bring the exposure into the two stop range and the
second). Luna-Pro F indicates an exposure at f4.
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to the effect of shutter speeds. The circuitry of your 2. Measurement of the ambient light only, with the
Luna-Pro F is designed to indicate the f/stop which Luna-Pro F in the ambient/daylight mode.
will produce correct overall exposure with a shutter
speed of 1/100th to 1/125th second. lf the ambient 3. Compare the different f/stops indicated for a
light is extremely bright, and a different shutter shutter speed of 1/125th second in flash and am-
speed is used, the indicated f/stop may have to be bient modes. Any difference between the two
modified to compensate for variations in ambient readings calls for an f/stop modif ication as shown
exposure caused by the change in shutter speed. in the following table:To determine if compensation is required, two
parallel measurements must be taken from the Example:
same position:
Luna-Pro F indicates f8 for a f lash reading and f5.6
1. Normal measurement (flash and ambient light) at 1l125th second for an ambient/daylight reading. difference f5.6) (f8 and is one shut- stop. lf thewith the Luna-Pro F in the flash mode. The '1l500th ter speed to be used increased is second, to
2. Measurement of the ambient light with the Luna- the table below indicates that the lens must be f rom the reading indicated byPro F in the ambient/daylight mode. opened up by 2/3 stop the Luna-Pro F. The higher the shutter speed
3. Compare the different f/stops indicated for a (1/500th second vs. 1/125th second) will decreaseshutter speed of 1l125th second in flash and am- the ambient light contribution to the exposure.
bient modes. Opening up the lens 2/3 f/stop will increase the am-
bient light contribution, bringing the ambient/f lash
Any difference between the two readings calls for ratio back to the original.
an f/stop modif ication as shown in the table below.

1. Combined measurement (f lash and ambient light)
with the Luna-Pro F'in the f lash mode.
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Reading difference                     Modification of f/stop setting
         between flash and                           (fractions ol f/stops)
          ambient readings                  with camera shutter speed setting:
                                             '1125 -  1130    1/50 - 1/60                                                                            '1t200 -  .1t250                                                                               1/400 -  1/500
                                  close down  close down     open up      open up
              1 stop                             1               1t2                  'll3             2t3
              2 stops                  2t3              1/3               1/6               1/3
              3 stops                   1/3              1/6             1/10              1/6
              4 stops                  1t4                 1/1 0             0               1/10
              5 stops                 1/10             0              0              0

ll. n. Color Crossover
The preceeding discussion concentrated on the ef-          individual color layers of the film can result in a
fects that lighting can have on  f ilm, either black and         condition called color crossover. This condition
white or color. However, with color, three separate          results in a color shift in an area of under or over ex-
emulsions are on the  f ilm each of whose individual         posure that cannot be corrected without affecting
response may be different. In normal exposure        the colors of the properly exposed areas of the
situations all three layers will track reasonably        scene. lt is therefore very important to avoid this
well, resulting in accurate rendition of color as well         condition which shows itself as color shifts in the
as density. However, at the extremes of exposure       shadows and highlights.
levels, deviations in the characteristic response of

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lf . o. Zone Systems The Luna-Pro F is well suited for use with most zone systems because of its null meter principle of
There are times when the lighting range cannot be operation and the zone system scales (20). Most
brought within the acceptable limits of the film systems are based on a central zone, representing
because of an inability to f ill or use "gobos" such a certain lighting level, called Zone 5. From this
as when photographing landscapes. When these level, the range of light f rom highlight to shadow is
situations arise, the exposure levels can be ad- measured and referred to this central zone. The
justed so that the most important parts of the level of variance from the central zone determines
scene receive proper exposure. This can be done the amount of exposure correction and processing
with either black and white or color film. However, modification, if any, that is needed. With most
some detail, either in the highlight or shadow areas, meters, the zone equivalents must be marked on
will be lost. the f ace or transferred to another sheet to correlate
with changes in light level. However, with the Luna-
When using black and white f ilm, another Pro F, the computer dial can be used to adjust the
technique is available to extend the capabilities of meter needle at any light level. Any subject can be
the film to record extreme lighting ranges. lt is nulled for and light variations fiom that level read in
called the zone system. Instead of relying on zone system values I thru lX directly off the meter
standard measurement and exposure techniques, face in EV. This means that you can always set null
the zone system combines special measurement tor Zone 5. Or, you may wish to bias the reading in
techniques, modified exposures, and altered film one direction.
processing to expand the range of light values that
the film can accept. In doing so, detail can be Simply turning the computer dial of the Luna-Pro F
recorded which would otherwise be lost. allows you to put the meter needle anywhere from
-3 to + 3 EV f rom a normal value.
A complete discussion of this technique is far
beyond this manual. References are given in the ap- To use the zone system scales of the Luna-Pro F,
pendix which should help you become familiar with take a measurement of a central zone (Zone V),
this very useful photographic tool. noting the corresponding EV values for each zone
27

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