SPECTRA UNIVERSAL P 250 User manual

INTRODUCTION
            Congratulations, and welcome to the world of SPECTRA. You are in distinguished
          company. SPECTRA meters are used by knowledgeable professionals the world
            over; from the swamps of Asia to the fashion studios of New York; from the
          movie studios of Hollywood to the industrial plants of Europe.
         SPECTRA INCIDENT-LIGHT meters are so called because they measure all the
                                                                                                   of                                                                            explanation                                                          (For                                                                    detailed                                                    a                                                     subject.                                           the                                 incident upon,                    falling on             light                           - or                                                            RESEARCH                                              PHOTO                                        your                                                 dealer                                                            for                                                      the                principle                                    ask                              Incident-Light         the                     of
            publication "lncident-Ly"). Now, get the "feel" of your meter. Twist the swivel
           head, note how you can point it in any direction while reading the meter scale.
          Examine the meter scale, the upper numbers indicate footcandles, the lower
          number f/stops. Insert a multiplying slide, note its effect on the meter reading,
              try an ASA INDEX slide.
          Look at the white Photosphere. Since the Photosphere receives all the light
             falling on the subject, it is an almost perfect 3-dimensional duplicate of the
            subject. Remove the Photosphere and see the light sensitive area underneath.
        Now that you have "met" your meter we suggest you make some actual tests
         on film. Experienced photographers know that all variables must be considered
         when determining correct exposure . . . film sensitivity, actual shutter speed,
             lens apertures, lens transmission, processing.
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              t
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Take time to make and record some tests. This will help you control or eliminate
the variables and enable you to get accurate and dependable results out of ypur
exposure meter/camera combination.
lf you are used to a reflected-light meter the change to an incident'light meter
may require a slight mental adjustment. You will find it much easier and quicker
to take readings. Your exposures will be more consistently accurate and the
troublesome "angle of acceptance" associated with reflected-light meters need
no longer be considered.
POINTER LOCK: (Figure 5 - Page 17)
Some SPECTRA meters are fitted with a pointer lock device. The Pointer Lock
button (11) is located on the front of the meter immediately'under the name
plate.
In the normal position the meter is locked.
    NOTE: lt is good practice to lock the pointer whenever meter
                 is being shipped or is not in use.
To Use Pointer Lock:               To Disengage Lock:
                                                                                                                                                                                                                         .1) Gently press down red button.   1) Gently press down red button and . .
2) Take reading while holding down 2) Rotate button r/a turn clockwise.
   button.                           Reverse procedure to re-engage lock.
3) Release button to hold reading.

                                                            3

ZERO AND BALANCE:
 Af f meters are correctly balanced and zeroed before leaving the factory. Zero
 adjustment should ngt be changed unless meter goes off zero.
TO CHECK ZERO: (Figure 1 - Page 4)    A) Insert blank slide in meter.
    B) Lay meter down on flat surface.
    C) Meter should indicate "O" precisely.
              lf adjustment is required, turn ZERO adjustment screw (7) as needed.
TO CHECK BALANCE:
    A) Insert blank slide.
    B) Hold meter in operating (upright) pcsition.
    C) Meter should indicate "O!'
            lf meter is off balance, see your SPECTRA dealer or have your service
      man adjust  it, otherwise inaccurate readings may result.
                        Page 4)SWIVEL HEAD: (Figure I -The swivel head (No.  f ) may be turned almost 36O' This allows unobstructed
use of the photocell while, at the same time, permitting a full view of meter
scale.
    cAUTloN: when using swivet head, Do Nor FoRcE rr BEyoND ButLT-lN
            STOP POINTS!

METER SGALE: (Figure 2 - Page 6)
Your SPECTRA has a dual meter scale -  footcandles on the top and f/stops onthe bottom. As you will see, this is a very useful feature of your meter.
    NOTE WELL THIS RULE: Read f/stop scale only when an ASA slide
                                       is in meter.
For reading intermediate values on the meter scale, refer to Figure 2-Page 6.
HOW TO MEASURE TNCTDENT LrcHT (PHOTOSPHERE):
Hold SPECTRA Meter at position of principal subject (or interest-center of scene)
and point Photosphere directly at camera lens. DO NOT POINT PHOTOSPHERE
AT SUBJECT. Rotate Photosphere to avoid shadows or reflections from photog-
rapher's clothing. Body of meter may be rotated for convenience without
affecting reading as long as Photosphere points at camera lens.
Follow this general procedure:
    1) The meter is held with the meter-scale toward the user.
    2) The swivel head is turrfud and pointed directly at the light being
        measured.
    3) When light level is too high (pointer goes over scale) a MULTIPLIER  is
         inserted in slot in swivel head.
For specific techniques and use of ASA slides for direct reading see Page 9.

                                                             7

Readings may also be taken near camera so there is no need to approach the
subject. This is especially useful in hazardous situations, or in distant scenes.
make certain that the light falling on the Photosphere is the sarne as the light
talling on the suby'ect, as the camera "sees"  it.
    NOTE: The Photosphere eollects all light falling on subject and integrates
                   it into one overall reading. (For balancing light, see Page 14.)
MEASURTNG REFLECTED LtcHT (W|TH PHOTOGRID):
When the Photosphere is replaced with the Photogrid (see Accessories, Page
22),the SPECTRA becomes a reflected light meter. This method is recommended
when it is impractical to use the Incident-Light method. Do Nor USE AsA
SLIDES      WITH THIS METHOD.
                                  ?&Q/. orProcedure:
    1) Remove Photosphere and snap Photogrid on meter.
    2) Point Photogrid AT THE SUBJECT and note reading. For black and white
        photography the shadow areas are generally the most critical. ln color,
        the highlight areas call for the most careful reading, as they will "wash
        out" if overexposed.
    3) Compute the exposure as detailed on Pages l1-13, using the Reference
       "DOTS" on the Computer.
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SLIDE SYSTEM:
An important feature of your SPECTRA is its unique SLIDE SYSTEM. Slides
furnished with your meter are part of the calibration of this meter and should
not be used with any other.
       NOTE: Direct reading without slide = 1200 ASA @ USO second.
There are two basic types of slides:
      f) ASA Index slides and,   2, Multiplying slides.
 It is important to understand the difference between the two.

ASA SLIDES:
ASA slides program your meter for direct f/stop readings at pre-selected shutter
speeds. These slides have the film ASA index engraved on the tab and are gener-
alfy (though not always) calibrated lor l/50 second shutter speed corresponding
to standard 24  f .p.s. on motion picture cameras.
   TO USE: Insert the appropriate slide ALL THE WAY into the meter (2), take
               reading in the usual way (Page 7), and read your f/stop directly
             from meter scale (Figure 2 - Page 6) - bottom numbers - with-              out referring to the computer.

                                                      9

M U LTIPLIERS:
Multiplying slides are used when the light level is greater than the full scale
meter reading of 25O fc. The XlO is generally used for brightly lit interiors,
studios, etc., and the X1O0 for daylight outdoors. With Combi-500 a special Red
XIO slide is provided for use with Booster. Multiplying slides are used with
the footcandle (upper) scale (Figure 2) and the marks X10 or X100 on the com-
puter (Figure 3). They cannot be used for direct f/stop reading, but note the
following important exception. On each multiplying slide an ASA number is also
engraved; XIOO has 12 ASA, XIO has 125 ASA, making these dual purpose
slides. When these slides are used for their ASA values, and not a$ multipliers,
you may read the f/stop direct, as you would with any standard ASA slide.
READING METHODS:
There are two methods of obtaining a reading on the SFECTRA meter: The
DIRECT method and the COMPUTER method. The Direct method is used ONLY
when ASA index slides are in the meter. The Computer method is for use with
XlO and X1O0 multiplying slides or when the meter is used without slides.
THE COMPUTER: (Figures 3 & 4 - Pages 12 and 15)The Computer consists of 3 dials (2 movable and I fixed). On the large movable
diaf (Figure 3) there are several reference marks. The arrows are for incident
light readings (Photosphere/Photodisk) and the dots are for reflected light
readings (Photogrid). Use as follows:

                                                               11

ARROWS    (lncident Light)              *Gombi Only                       -
              Black Arrow     No slide in.   Red Arrow    Booster on. N.o sride in.
              Black X'10 Arrow XlO slide in.  Red Xl0 Arrow Booster on. Red XlO slide in.
              Black Xl00 Arrow Xl00 slide in.
           DOTS (Reflected Llght with Photogrid):       *Combi Only
           One Black Dot  No slide in.    One Red Dot   Booster on. No slide in.
           Two Black Dots X10 stide in.   Two Red Dots Booster on. Red Xtr O slide in.
             Three Black Dots XIOO slide in.
                                                            * Combi users see further Instructions page(s) l6-21
           The computer center dial ("8" Figure 4) is used for setting film speed. Shutter
             speeds and cine frames per second are also marked on this dial. Markings are in
            seconds and fractions thereof. Intermediate speeds on this dial are shown in
           Figure4-Page l5).
           The upper dial ("c" Figure 4) shows light values on the top and f/stop on the
'l            bottom. Intermediate values on this dial are shown in Figure 4 - page 15.
          SET FILM SPEED:
 I             Hold meter in left hand and line up ASA tab (Figure 1) in ASA window on com-
               puter; apply slight upward pressure (with thumb) on ASA tab and rotate knurled
              disk of computer (with right hand) to bring appropriate film speed into window.
             Release pressure on tab, film speed is now locked in.


                                                                                                                                                                                                                                                                                    )
                                                                        13

Having taken a reading and noted the light intensity (footcandles):
      l)  Rotate dial A and align appropriate reference point with light value on
          dial C. (See pages 12 and 15).
    2) Read off any of the various combinations of shutter speeds and lens
        openings indicated by the computer.
The Cine scale (Dial B) shows frames per second opposite the lens apefture for
those using motion picture cameras.
BALANCING THE LIGHT (PHOTODISK):
                                                                                                          isThe ratio of highlight to shadow is generally a matter of personal choice. lt
easy to achieve any desired lighting contrast with the use of the PHOTODISK on
your meter. (See Accessories, Page 22).
           f ) Remove Photosphere and snap Photodisk on meter.
    2) Insert multiplying slide, if needed (Page 11).
    3) Hold meter at subject and point Photodisk directly at key light. Note
                                        i ntensity (footcand les).
    4) Hold meter at subject and point Photodisk directly at fill light' Note in'
         tensity (fc).
    5) Adjust lighting ratio as needed. Example: Key light reads 32 fc. and the
         desired ratio is 4:1, adjust  fill to read 8 fc.
    6) Exposure reading is made by replacing disk with Photosphere. Read as
          usual.           www.butkus.us
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COMBI BOOSTER CIRCUIT: (Figure 5 - Page 17)
When the level of light falls below the normal sensitivity (10 fc. or fess) of the
COMBI-500, a "boost" of lOO times sensitivity is obtained by switching to the
CdS booster circuit. (Figure 5).

The Booster "ON" switch (8) is located at the side of the swivel head' The
switch (9) at the top of the swivel head is for checking batteries.
Characteristically CdS photocells do not react to light as quickly as Selenium
cells, therefore, when using Booster, keep "ON" button pressed for approxi'
 mately 5 seconds while taking a reading.


LOW LIGHT LEVEL PHENOMENA: (CdS Cell)

When the COMBI.5OO is used to read very low light levels, and the blank slide
 has been in the meter, or the metei has been in its case, it is advantageous to
 ,,condition"             the CdS cell by exposing it to a light of slightly greater intensity than
 the one being measured. Due to basic characteristics of the CdS cell, there is a
 ,'recovery"           time of a few secondswww.butkus.usbefore the reading is stabilized. Where critical
 measurements are required, repeat the reading after a few seconds interval.
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BATTERY TEST: (Figure 5 - Page 17)                l) Press battery test switch (9)."             2) Pointer should read at the 54 footcandle mark   or to the right of it                                                                   -                    -                   on the meter scale.
             3) Replace batteries  if pointer reads less than 64 fc. mark..        REPLACE BAfiERIES:
          COMBI-500 Booster uses two 1.34V Mercury batteries (button type), mounted in
          a spring loaded slot in the swivel head. To replace batteries:
               1) Push battery holder out (with large coin) of battery slot. (10, FlG. 5)
             2) Place new batteries in holder. Observe pglarity (etched on holder and'
                 on batteries).
             3) Hold meterwith photocell facing down.
             4) Insert battery holder into slot with notched side of holder aligned with
                    "step" in slot.
-       COMBI-500 GG PHOTOREADER: (See Accessories Page 22)
          The SPECTRA GG (Ground Gtass) PHOTOREADER  utilizes the ultrasensitive CdS
              cell of the COMBI-500 to measure the actual brightness of the image on the
          camera ground glass. lt may also be used with SLR cameras through the view-
I            tinder.
                        Betore usfng the GG PHOTOREADER  it is necessary
                              to match it to the equipment in use.

                                                                     19

CALI BRATION: (Photoreader)
1. Make a typical photographic set-up, using the same equipment which will be
   used with the GG PHOTOREADER.
2. Determine correct exposure in the usual way. (Do not use GG PHOTOREADER
    for this.)
3. Set computer on the COMBI-500 for correct exposure.

    NOTE: RETATN THIS "REFERENCE SETTING" THROUGH STEP 8 UNTIL
                                                                                                                                    {          CALIBRATION IS COMPLETED.

4. Attach GG PHOTOREADER to meter.
5. Open up fully the tens aperture on camera.
6.  Hold GG PHOTOREAD.ER firmly against camera ground glass or SLR eyepiece.
   (Use focusing cloth to exclude extraneous light.)
7. Press CdS switch and note light value (upper meter scale).
8.  Locate this same light value on upper dial C of Computer. Opposite this value
   scribe a reference mark on large movable dial A. (Be sure "REFERENCE
   SETTING" is still set as in STEP 3.)
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The meter is now calibrated for this particular camera/tens combination. This
 GG reference mark is valid so long as the equipment remains the same. A new
 reference mark must be established whenever the lens or ground glass is changed.

TO USE THE GG PHOTOREADER:
 l. Hold PHOTOREADER  firmly against ground gtass orByepiece. (use focusing    cloth to exclude extraneous light.)

                                                                                   ,,spot,, 2' Take reading. When the subject has a wide tonal range several                                                                                    read-
    ings may be taken over the ground grass area and then averaged out.
3. On Computer set GG reference mark opposite reading.
4. Read off exposure from computer setting.

Because the GG PHoToREADER measures the light at the focal plane, it auto-
matically compensates for lens transmission,  filteis and bellows extensions. The
GG PHOTOREADER is particurarry usefur in the fierds of photomacrography,
photomicrography, telephotography and the graphic arts.

                                                           2L

CARE OF THE METER:
Your SPECTRA meter is a precision pivot and jewel instrument. lf used with
normal care it will give many years of reliable service. Treat it like any fine pre-
cision instrument. Avoid excessive shock or vibration, do not drop, do not store
 in gfove compartment of car, near radiators or other hot places.
When storing COMBI-500 for any extended period, always remove batteries,
never leave worn-out batteries in meter.
The words SPECTRA, PHOTODISK, PHOTOGRID, PHOTOSPHERE are
registered trade marks of the PHOTO RESEARCH COBp.
GUARANTEE:

SPECTRA meters are guaranteed for one year against all defects of material and
workmanship, provided the REGISTRATION CARD accompanying the instrument
 is filled out and mailed to us within 30 days after purchase.

The guarantee does not cover damage due to accident, misuse or tampering.

Distributors throughout the world
A Product of
PHOTO RESEARCH CORP.                                      Burbank, California, U.S.A.
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                        MANUAL NO. 3.0T4