Sekonic L-508 quandary

Discussion in 'Lighting' started by malinmalin, Oct 7, 2007.

  1. malinmalin

    malinmalin Member

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    Hi,

    Just got a Sekonic L-508 and while I was playing with it something strange
    just happened: I've setup a strobe to test it and made a measurement.
    Say at iso100, f/11 for 1/500s. Oups. I usually try to sync between 1/60s
    to 1/125s (I shoot with a 6x6 with a blade shutter so sync speed is not an
    issue but readon). So I change the speed to 1/60s, and redo a measurement
    at 1/60s but the meter gives me the same f-stop, f/11!?! To convince myself
    I havent completely lost my mind, I've done a series of measurements,
    changing the speed from 1/30s to 1/500s but the meter always gives the same f-stop value.
    Am i overlooking something really simple?

    thanks
    jf
     
  2. patrickjames

    patrickjames Member

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    The meter is reading the light output of the strobe, so the time you input doesn't have any effect on the exposure. Change the ouput setting on the strobe and you should see a change in the reading. Your meter is fine.

    Patrick
     
  3. John Koehrer

    John Koehrer Subscriber

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    The speed of the flash is much faster than you're using on the camera.
    The flash exposure may be 1/5000th or more so the speed setting on the shutter doesn't matter.
    It will on a focal plane shutter only because the shutter needs to be completely open at the time of exposure.
     
  4. malinmalin

    malinmalin Member

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    Thanks for the bullet-speed replies!
    But then what is the relation between the meter measurements
    and my camera settings?
    I feel like I've living in darkness all this time :smile:


    jf
     
  5. Nick Zentena

    Nick Zentena Member

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    How dark was the room. At a slow enough speed you'll gain something from the room light. How slow depends on the power of the strobe and the room light. Try turn down the strobe to low power and repeat the tests. Other then that what the other guys said.
     
  6. walter23

    walter23 Subscriber

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    In flash lighting, as mentioned, the flash output is a tiny fraction of the time your shutter is open. With flash, the flash output brightness (and/or location, as they're obviously related), and the f-stop you're shooting at, are the exposure variables of importance (ignoring the issue of using fill flash with ambient lighting).

    So, if you want a particular f-stop (for DOF purposes or whatever), you have to change your flash output intensity instead of your shutter speed. If you have a set flash output for whatever reason, then you change your f-stop to get the right exposure (stop down if your flash is too bright, etc).

    Shutter speed has no impact, because the flash virtually instantaneously "pops" and puts out all its light in a fraction of the time your shutter is open. Doesn't matter if you're at 1/60th or 1/200th - your film or sensor will catch the same amount of light from that instantaneous flash pop.
     
  7. JasonC

    JasonC Member

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    Shutter speeds comes into play if you want to mix both flash and ambient lights. In this case, shutter speeds determine the amount of ambient light.

    Jason.
     
  8. malinmalin

    malinmalin Member

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    Yesterday I sat down and thought about all this and I came
    naturally to the same conclusion regarding the flash output
    time versus the time the shutter is open. It now makes perfect
    sense. I feel a little silly to have asked such a question!

    Thank you all for your comments!
    jf