METROVICK photo-electric User manual

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INSTRUCTIONS
       FOR USTNG THE
  METROVICK
   PHOTO - ELECTRIC
 EXPQSURE METER
  STANDARD i'nrrenru  \

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The Metrovick electric exposure meter enables the photo-         over'-exposure.l                will result. The horizontal and vertical fins
grapher to ascertain the correct exposure to give under         fitted across this window are designed to limit the angle of
practically  all lighting conditions.                                                                                     ' ligh.t falling on the cell, to the angle of the average camera lens,
The meter comprises a highly accurate electrical measuring        and thus toleliminate inaccuracier arising, for example, from
instrument and a photo-electric cell which generates a current        the inclusion of too much sky..
proportiorial to the intensity of the light falling upon it through       The meter scale is arranged to indicate the duratlon of a full
the window in one end of the case. The reading of the index        exposure and not, as is the case with some meters, a minimum
pointer is directly proportional to the intensity of the light.         exposure forming a basis for a.calculation by the user.
The photo-electric cell is constant in performance and. does                                                The scales are direct reading for an aperture of. lt/8 aninot require renewal unless mechanical ly damaged,. No                                                                                                                             t?o                                                    Ibattery or other external source of current is required.          an emulsion (or film) speed of 23" Scheiner (or    DIN)                                                                                                                                                                             ,f
It is important that the window over the photo-electric  cell       For other apertures and _emulsi6n speeds the corwersion
be kept clean.  lf this is not done, incorrect readings leading to           scales, mounted in the lid of the leather case must be used.
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                                                     www.butkus.us(\.                                                                                                                                                                                                 av)?HOW TO USE YOUR EXPOSURE METER             lnrn
(1 )  Point the cell window of the exposure meter towards the sublect to be photo-
    graphed, as thouth  it were a camera, and note the value indicated by the pointer
   on the black scale.
        lf che light is too poor to give a readable indication on the black scale, press the red
    butron in the right-hand corner ofthe meter and take the reading on the red scale.
     Pressing this button increases the sensitivity of the meter 50 times.
(2)  The reading so obtained is the exposure in seconds to be given whenrusinS an
    aperture of F 8 and an emulsion of which the speed is 23 Scheiner (orii   Oltlt.
    For other apertures and emulsion speeds, see pages 5, 6 and 7.
(3 )   lf the subject has large areas of great contrast such as deep shadows and a bright
     sky, it is advisable to take a reading for each by inclining the window towards each
     in turn. The exposure to be given can then be selected to suit that part in which
    rhe most detaii is desired.
    NOTE.-Forsubjects  including a large proportion of sky (more than 75':,, oI picture
    area) ir is somerimes advisable to incline the meter slightly towards the ground, so
     rhat the sky shall not have an unduly great influence on the reading and so lead to
    under-exposure of the foreground
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     HOW TO USE THE  CONVERSION SCALES               t
 tfthe speed of the film in use differs from 23o Scheiner, or the           " Meter Reading." The exposure related to each of the
aperture F/g cannot be used, the exposure related to iarious          standard F numbers can then be read off the lower scal e
apertures and film speeds can be read off the conversion scates         marked " Exposure Scale."
efter setting them in the manner described below,                   (3)  lf the F number  it is proposed to use appears against
                                                    a shutter speed thirt is not obtainable on the shutter    (1 )  Set the lower disc so that the Scheiner number of the                                                                     of the camera enrployed,  it  is advisable to select a       film in use appeaFs in the small window under the slot                                                                     shutcer speed that is obtainable and to use the corfes-        in the upper disc.                                                                    ponding F number.  lf the shutter operates satisfactorily
  (2) Turn the upper disc until the arrow D on the edge        between the speeds marked upon it, as many do, this
       points to the meter teading on the top scale, marked          situation will not arise.

                               SEE DIAGRAMS ON FOLLOWING PAGES.

                                                                                                     Pace 5

ExomPle (11
            Emulsion Speed 23 n Scheiner. Meter reading 1/50 second'
           (a) With the lower disc set so that 23 appears in the
              window
          (b) Set pointer D  to    1/50..........
          The cxposure for any aPcrture can then be read off the
         axposuro scale
            Thus, for Fl 1 the exPosure is 1,25 secold : for F5 '6 it is
              1,'10d second, and so on. For F8 it is 1/50 second as read
              dircctly from the moter scrlo.


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Exomple (2)                                                                                                                                                                                                                      t/ltta
        Emulsion speed 20' Scheiner.              Apertu re F8.    ]nr/)        Meter reading 1/50 second.
   With the lower disc set so that 20 appears in the window, ser
    pointer D to 1,50, and the exposure opposite F8 on the
    aperture scale will be found to be 1r25 second.  (See FiC. on
      right.)

Exomple (3)
         Emulsion soeed 26' Scheiner.             Aperture  Fl 1.
        Meter reading 1 '100 second.
   With the lower disc set so thar 26 appears in the window, set
    pointer D to 1/100 and the exposure opposite to F1 1 will be    found to be 1 100 second.


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                ARTIFICIAL LIGHT PHOTOGRAPHY

                       The Metrovick Photo-Electric Exposure Meter is calibrated to give accuratc
                          readings when used with lncandescent Electric lighting.  (Gas-filled
                           lamps or over-run filament lamPs.)
                       Care must be taken that direct rays from the source of light do not fall
                      on the cell window of the meter or incorrect readings will be obtained.



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                        Thc Mctrovick Exposure Meter is manufactured in oneof
                                 the largest elcctrical instrument factorict'in Great Britain by
                             METROPOLITAN.VICKERS  ELECTRICAL CO. LTD..





5,000.9.{6                                   Form R23@                                                         1.8.5342/11