Lightmeters used in USA vs Europe

Discussion in 'Lighting Equipment' started by proy, Jun 2, 2015.

  1. Hi. Just a very simple question: I've got a Sekonic L-758Cine meter which I bought in Canada. Just wondering if the readings of light can differ whether I'm based in America or Europe (i.e. 50Hz vs 60Hz) ? I'm thinking it doesn't matter! I just need to set my meter to either 25fps or 30fps (in video mode), depending on where I'm at... but please do correct me if I am wrong, and if so, what should I look at in my meter ?
    Thanks very much.
  2. Light meters run on batteries, not AC line current, so 50/60 hz has nothing to do with light meters.

    24/25/30 fps are settings used when using a light meter with a movie camera using film. The frames per second, along with the shutter opening, determine the shutter speed in a movie camera. If you were using a light meter with a video/TV camera, you would most likely be measuring footcandles or lumens to set lighting ratios, not actually taking a ready for exposure purposes.

    In short, being in America or Europe has nothing to do with how you use a light meter.
  3. That's what I thought. Thanks Craig :)
  4. Only time it makes a difference is when you are using a pocketwizard module in your light meter.
    Pocketwizards use different radio frequencies depending on region. And a US pocketwizard radio module wont work in a Euro sekonic light meter and vice versa.
    Different fps is used to avoid AC flicker from lights and the frequency of the AC mains is what is used as a base for PAL and NTSC broadcasting standards as well. So 30 fps is used in the US and 25 fps in Europe.
    So if you set you video camera for instance to 25p (25fps) you need a shutter speed that is 1/25s or faster. This is how most DSLR/mirrorless camera settings work when shooting video.
    The cine versions of Sekonic meters have shutter angle and other bling bling for cinematographers but you can convert between shutter angle and shutter speed yourself too. Same with lux, footcandles too. If you have EV (and every digital Sekonic do AFAIK) you can use a table in the Sekonic manual to get lux and fc.
    Actually if you have an EV reading you have enough information to to set your ISO, aperture and shutter speed but it requires some mental gymnastics. Or you can use a table for that as well or let your light meter do it for you with some button gymnastics.
  5. The line frequency can affect the colour rendering and evenness of illumination for stills too. Standard single-phase mains lamps (i.e 99.9% of what you'll come across) flicker at 100 or 120 Hz depending on whether the mains frequency is 50 or 60 Hz. If the shutter speed used is much shorter than the flicker frequency, then you don't capture an entire pulse of light from the bulb or tube and the colour and/or exposure may vary across the frame. With fluorescent or discharge tubes this is almost certain to happen. Filament bulbs are a bit more forgiving.
    Same thing happens with meters if they're the type that electronically gates the exposure reading according to the shutter speed set. The gated reading could easily vary from button-press to button-press. These are mostly flashmeters or meters used in flash-metering+ambient mode though. And with these you have to set the intended shutter speed before taking a reading. If the meter allows you to vary the shutter speed after you've taken a reading, then there shouldn't be a gating-time issue.

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