Lunasix F. Sekonic Twinmate. How accurate is "accurate"?

Discussion in 'Lighting' started by elerion, Apr 21, 2017 at 3:34 AM.

  1. elerion

    elerion Member

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    I've got an old Lunasix F, which works fairly well.
    I just compared its readings with a new little Sekonic Twinmate.
    The Sekonic usually reads about 1/3 or 1/2 stop higher.
    They are so close, that I don't know how to decide which one is really spot on.

    Digital images taken with both reading look perfect. Histogram could help. But digital cameras are not usually ISO precise.

    Analog images are great too, as expected, but developing adds some little unavoidable offsets in density, so I cannot use them to determine which reading is "the good one".

    Checking the light readings against an old EOS 500 (only reflected mode, of course), it matches those of the old Lunasix F.

    I thought that a new meter should always work better than an old one.
    Is it feasible that the new Sekonic is not as precise as the old Lunasix F?
    or is it most likely that the old meter needs some recalibration?
     
  2. AgX

    AgX Member

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    It depends on the circuit and the used types of electronic elements. In some circuits only elements are used that hardly age. The resting troublemaker then could be the contacts.
     
    Last edited: Apr 21, 2017 at 3:46 AM
  3. bdial

    bdial Subscriber

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    a 1/3 - 1/2 stop difference isn't significant.

    There is no real standard that light meters are calibrated to manufacturers get to choose their own, so a small difference between a Sekonic and a Gossen isn't surprising.
     
  4. benjiboy

    benjiboy Subscriber

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    I think the minor discrepancy an the exposure readings can be accounted for by the the difference in the two meters acceptance anges, the Lunasix F.s being 30° and the Sekonic Twinmate being 33° and so small to be insignificant.
     
  5. AgX

    AgX Member

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    Not true.

    In the past there was DIN 19010 in 3 editions.
    Now there is ISO 2720:1974-08.
     
    Last edited: Apr 21, 2017 at 9:07 AM