Bewi Super L Meter

Discussion in 'Lighting' started by janaby, May 23, 2013.

  1. janaby

    janaby Member

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    I'm thinking of buying a Bewi Super L light meter but before i need to know if it gives exposure values of more than 30 minutes.
    I've tried to look for this information but nothing so far, hope anyone here can help me.
    thank you
     
  2. AgX

    AgX Member

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  3. janaby

    janaby Member

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    hm...
    I'm going to photograph with ektar 100, inside a camera obscura
     
  4. bernard_L

    bernard_L Member

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    In general, a lightmeter will not give you directly exposure times in 10's of minutes. Neither will it have provisions for the f-numbers of a pinhole camera (camer obscura). But that is the easy part: say, meter indicates 1/125 f/16.
    "Equivalent" (read below) exposures: 1/2sec f/128, 1sec f/180, 2sec f/256, etc... but only a starting point.

    The hard part is reciprocity law failure. And the meter won't help, even if it has markings up to 30min and f/256.
     
  5. janaby

    janaby Member

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    the link you sent is for the Bewi Super, the one i am talking about is the Bewi Super L...
     
  6. janaby

    janaby Member

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    yes, the reciprocity failure is yet another thing i'm trying to solve. can't find experiments on more than 5 minutes exposures
     
  7. janaby

    janaby Member

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    I'm am shooting with a Sinar, inside a camera obscura (my room) so the f-numbers are not the pinhole. I just needed to know if the Bewi Super L would work in such a weak light...
     
  8. AgX

    AgX Member

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    -) to my knowledge (Internet...) the Super and the Super L have the same metering circuit

    -) I don't know the sensitivity of that meter. Someone could check against one of those most sensitive meters. But that won't help you as you don't know yet the luminance in question...
     
  9. janaby

    janaby Member

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    i'm not really pro in this photographic concepts: what do you mean with luminance?
    I've already made some photographs in the dark room but with digital, i know to relation between the sensitity of the digital to the analog is not very diferent (except in the reciprocity failure thing), i am now simullating with the digital what may happen with the sinar...but it still isnt very accurated
     
  10. AgX

    AgX Member

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    Luminance = "Brightness" of your subject (in this case the reflection from your chamber wall.

    For proper working of that meter you need a mercury battery. Have you got one??
    (Or a well made electronic substitute?)

    I just checked my sample:
    the needle starts to move about 1/2 stop outside the range of that red digit one has to operate (which I intreprete of sign of good working condition).
    And that most extreme position is equivalent to

    1h @ f32 @ 100ASA

    The sensitivity of that meter would thus be EV +2 .
     
    Last edited by a moderator: May 23, 2013
  11. janaby

    janaby Member

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    No, one more thing to buy...
    Right now with digital I am shooting at ISO 100, f.10 and 1h30m
    if the meter only gives 1hour, with ISO/ASA 100 it would probably give f5...no?
     
  12. AgX

    AgX Member

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    It seems that Bewi Super meter is still within your range...