Gossen Multibeam Spot Attachment for Luna-Pro sbc User manual

MULTIBEAM SPOT ATTACHMENT FOR
GOSSEN LUNA-PRO sbc
The normal measuring angle of your Luna-Pro sbc is 30o. For most average
 scenes, this is ideal. However, in certain circufistances, a narrower angle of
view is desirable. The MU LTI BEAM Spot Attachment allows you to select
 eithe r 10o,50 or 1o to measure light levels of specif ic subjects or areas of a
subject when surrounding areas are significantly different in intensity. Scene
 brightness range measurements, zone system measurements and measure-
ments of distant objects can all benef  it from the use of this attachment.

 Note: Before reading the following detailed in-
structions, you should be completely familiar
with the general operating procedures outlined
in the Luna-Pro sbc Owner's Manual.

ATTACHING TO THE METER:

Slide the spherical diff user of your Luna-
Pro sbc to the right. Align the MULTI-
BEAM Spot Attachment with the front
of the meter so that the plugs on the
attach ment are opposite the jacks (F ig.
1,1) in the meter and the recess in the
attachment is opposite the hemisphere. While holding the MU LTIBEAM, push
the accessory straight onto the meter. When attach ing or removing the
accessory, make sure to pull or push straight out, otherwise the plugs or
jacks may be damaged. When attached to the meter, it automatically adjusts
the meter sensitivity so that direct readings can be taken without making
f u rther ad justments.                          www.butkus.us

ADJUSTING THE DIOPTER CORRECTION:
Look at a subject in the distance through the MU LTI-
BEAM Spot Finder, rotate the diopter correction ring
(Fig.1,4) until the measuring angle rings are sharp.
The diopter correction ring will now be set for your
eye at a correction  f rom -3 to +3. Record this value
for future reference.
SELECTING A MEASURING ANGLE:
The measuring angle of the MU LTIBEAM  is selected
by means of turning the measuring angle selector
 (Fig.1,2l to 1o, 50 or 10o. Look through the view-
finder (Fig. 1, 3) while pointing the MU LTIBEAM
at the area of the object to be measured. Determine       i$

which measuring angle as indicated by the indicator rings in the finder most
accurately covers the area you wish to measure. The outer ring indicates 10o,
the inner 50 and the central ring covers a 1o area. Turn the selector to the
appropriate setting. Red LED digits will be visible in the finder showing the
measuring angle you have chosen. tt't* full visible aYea covers 150.
TAKING T\ READING:
With the MU LTIBEAM Spot Attachment connected tn
your Luna-Pro sbc meter, you will obtain direct readi. -s
at whatever measuring angle you choose. Any ehange in
the measuring angle will automatically make the necess-
ary adjustment to the meter to compensate fOr the dif-
ferent light transmission at different measuring angles.
                                                                                                                                          r biectPoint you r M U LT  I B EAM Spot Meter at the "'
being measured. Activate the www.butkus.usLuna-Pro s*-- r.r! pressing

and releasing the power switch. A reading is then made and electronically
stored in the meter. While looking atthe meter, rotate the computer dial
until the meter nulls. Read any combination of f/stops - shutter speed
you desire f rom the calcu lator dial.
 lf the one minute time period of operation of the Luna-Pro sbc is too short,
the power switch can be locked on for continuous operation. Always re-
member to turn the power switch backto the normal position after using
the locked position, otherwise, short battery  I ite will resu lt.
APPLICATIONS:     EukrS, c,,g
The MU LTI BEAM Spot Attachment  is ideal for measuring light levels of
specific subjects or areas of a subject when surrounding areas are signifi-
cantly different in intensity. Scene brightness range measurements, zone
system measurements, and measurements  of distant objects can all bene-
fit from the use of this attachment.

SCENE BRIGHTNESS AND ZONE MEASUREMENTS:
 When doing scene brightness range measurements, the areas of highligh!and
 shadow can be individually measured and your total light range determihed.
  lf it exceeds the capabilities of the film to record, you may wish to hold
 back the light in the highlight areas or add supplemental light in the shadow
 areas.
                                                                                                                                                                                                                                                                                                                                                                                                         ' Choose the darkest area of the scene, take a reading and turn the dial of the
 Luna-Pro sbc untilthe meter needle is set at -3 on the meter face (under-
, exposure side).
 Now select the brightest area of the scene, press and release the meter on/
 off button. Without turning the dial, read the number of stops change on
 the meter face. This is your brightness range as expressed in f/stops.
 Further information for compensating or changing exposure is indicated in
 the Scene Brightness Range Section of the Luna-Pro sbc Instruction Book.                          www.butkus.us
 For zone system measurements, the technique of measurement is the same

as scene brightness except that exposure and processing may be modified
 instead of changing lighting ratios.
 Select an area of the subject that you want to be Zone5. Take a reading
 and null the meter. The null point on the meter now becomes the equiva-
   f ent to Zone 5. Then, by reading other parts of the scene, you can deter-
.mine approximate zones directly off the meter face with no adjustments.
 With normal processing of your film, each major division of the meter
 scale is equivalent to one zone.                         0rrfKos                                 "4  f .E. a reading of 2on the underexposure                                            side wou[O                                                 be equivalentto Zone 3
and a reading of 1 on the overexposure side would be equivalent to Zone 6.
 Using the null systeffi, you can quickly determine lighting ratios with no
 calculations at all. You do not have to worry about determining f/stop or
 shutter speeds or even ASA values when determining ratios. They can be
 read directly off the meter face and any point in the scene can be set as a
 zero reference or standard.

EVALUATING THE READING:
    A certain amount of care must be exercised when taking spot readings be-
      cause the total scene is not measured. All light meters are calibrated using
    an 187:o grey ref lective subject as a reference.  lf your subject is close to this
      .value, the reading can be used directty. However,  if your subject is unusual-
       ly light, you may want to increase your exposure by 112to 1 f/stop. This
        is because the meter will correct the subject to look as if it were a grey sub-
      ject. Increasing the exposure will bring  it closer to a lighter value. Similarly,
         if your subject is unusually dark, you may wish to decrease your exposure
    by 1 12 to 1 f/stop from the indicated reading to get it closer to its original
     value. With a little experience, this type of evaluation will become second
      nature to you.
    On the back of the MULTIBEAM Spot Attachment is a scale showing
     the maximum sensitivity (minimum light level that can be measured) for
     each measuring angle.        www.butkus.us

10

LIGHT PATH
 1. Lens
 2. Beamsplitter mirror,which divides
    the light into a measuring and view-
     finder beam
 3. Lens
 4. Reversal mirror for measuring beam
 5. Apertu re of the Lu na-Pro sbc
 6,7 , 8. R eversa I m  i rror  f or viewf inder beam
 9. Reversal lens for viewfinder beam
10. Viewfinder rings with LED readout
11. Viewfinder ocular
12. Apertures for adjusting measuring angle