How do film makers measure studio lights brightness?

Discussion in 'Digital Video' started by coneman5259, Jul 24, 2012.

  1. coneman5259 macrumors member

    coneman5259

    Joined:
    Sep 20, 2007
    Location:
    Chicago
  2. BillMidwest macrumors newbie

    Joined:
    May 25, 2011
    #2
    Lux or foot-candles; measuring incident - as opposed to reflected - light.
     
  3. coneman5259 thread starter macrumors member

    coneman5259

    Joined:
    Sep 20, 2007
    Location:
    Chicago
    #3
    A little more complicated than I thought, haha, thank you none the less.
     
  4. ytk macrumors regular

    Joined:
    Jul 8, 2010
    #4
    Actually, it's a bit more complicated than that.

    Your typical light meter will be set for a given sensitivity (ISO value of the film or digital sensor, taking into account any filters in place) and frame rate (usually 24fps, yielding an exposure time of 1/48th of a second per frame). The light meter will then report the f-stop value that will correctly expose the image. You can also measure absolute light values in terms of lux or foot-candles as mentioned above, but these aren't terribly useful on their own for obtaining an accurate exposure, so you'd usually just let the meter do the calculation for you. Hence, when measuring light, the person operating the meter will report that the light reading is an "f/8" or "an f/11-f/16 split", for example. This does not constitute an absolute measurement, however, so any change in the camera settings will necessitate a new reading.
     

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