Sekonic L-558 Cine - broken?

Discussion in 'Miscellaneous Equipment' started by OMU, Jan 4, 2011.

  1. OMU

    OMU Member

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    I have a Sekonic L-558 Cine. It works fine when using it in daylight, both ambient and incident light.

    When I use it in cord flash mode it shows the same f. stop regardless the speed I select. Unless I select some really slow shutter speed

    Am I doing something wrong, ore is something wrong with the meter?
     
  2. CGW

    CGW Member

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    Do you have the 558/558C manual? If not, it's available online.
     
  3. tkamiya

    tkamiya Member

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    Duration of light from flash is somewhere around 1/2000th and 1/4000th of a second. In flash metering, shutter speed has no meaning except for how much ambient light you'd get. If you move your flash closer or far, does the reading change?

    I thought, in flash mode, all light meter go into 1/60s or some arbitrary sync speed. Maybe yours is different.
     
  4. MattKing

    MattKing Subscriber

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    My Gossen Digiflash does require that I set the synch speed in order to accurately measure flash exposure. So it is possible that the OP's meter requires the same.

    I don't really understand why the Gossen works this way, but I expect that it has something to do with the internal logic of the meter, and not how the light from the flash actually works in conjunction with the settings on the camera.

    I'd concur with the suggestion to download the manual:

    http://sekonic.com/support/support_21.asp
     
  5. OMU

    OMU Member

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  6. Steve Smith

    Steve Smith Member

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    Yes. The flash duration is so fast the shutter speed is irrelevant (as long as it is not faster than the flash synchronisation speed).

    It could be that if the ambient light was high enough, it would take that into account too but it sounds like either your ambient light is too low to affect the meter or the meter does not do this.


    Steve.
     
  7. tkamiya

    tkamiya Member

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    Think about it this way. Shutter works to limit the amount of light coming into the exposure chamber (film) by opening and closing in short duration. By doing it at high speed such as 1/1000th of a second, very little light comes in. If you do it for 1/60th of a second, more light will come in.

    BUT, all this assumes the source of light (usually SUN) is continuous. If you are using flashes, they provide burst of light that is very short - sometimes as short as 1/8000th of a second.

    Visualizing,
    1) shutter opens, flash goes off for 1/8000th of a second, shutter closes 1/250th of a second later
    2) shutter opens, flash goes off for 1/8000th of a second, shutter closes 1/60th of a second later

    Does the amount of light from flash that hits the film change in case 1 and 2? No. ALL of the light from flash hits the film either way because while the flash was ON, shutter was wide open in both cases.

    (please note, you can NOT always do this with regular camera as sync speed of the shutter is sometimes slower - this is an idealized example only)

    What does change in those cases is the amount of ambient light that hits the film.

    So, if you are using flash, you change aperture to change exposure from flash and you change shutter speed to change ambient light. Using this creatively, you can control how much light your foreground objects get lit and how much background get lit.
     
  8. OMU

    OMU Member

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    Thanks to all of you.
    You can always leave your problems to APUG,
    "You will newer walk alone" :D