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Shooting 24p in 50Hz electricity system countries
  • LucasAdamsonLucasAdamson
    So, I have a GH2 and I live in the UK, a country with a 50Hz electrical system, and hence a 25p standard for shooting video and film. I am told that this can cause real problems with some lights, but having NEVER shot 24p before, I'm not sure whether the warnings not to shoot 24p here for serious work are important or not.

    Does anybody have any video examples of GH2 24p footage (or any 24p footage) going horribly wrong in PAL countries with 50Hz lights?
  • 14 Replies sorted by
  • alcomposeralcomposer
    @LucasAdomson
    I haven't had issues- as the shutter is more important than the frame-rate. If your shutter is not a multiple of the oscillation of the lights (regardless of what the lights are) then you will see flicker/strobing.
    Thus
    50hz = 1/50 or 1/100 shutter (1/100 for slowmo- or effect)
    60hz = 1/60 or 1/120 shutter (1/120 for slowmo- or effect)

    So make sure that you set the shutter to the above and you will be fine- DON'T mess with the shutter after that- high shutter values look horrible- except for effect- low shutter values look strange as well- but can be used once in a blue moon.
  • RRRRRRRR
    @LucasAdamson try shooting your desktop light f.i. - change shutter speed until you get flicker, unless it's there straight away. Then you see what it looks like.
    Don't worry too much about it, in 90% of the cases you will notice it immediately, and with a bit of experience you'll know when to look for the rest 10%. (when stray light manages to contaminate part of a shot)

    Just take care to do proper testing before doing an important shoot if you want to make sure that everything is A-OK. This is not just good for avoiding flickering light but good for avoiding all sorts of potential problems, foreseen and unforeseen.
  • John_FarragutJohn_Farragut
    I recall even some movies having flickering lights in scenes like underground parking lots, unless I'm mistaken. I have to review a couple of movies to make sure.
  • MeierhansMeierhans
    Tungsten light is most of the time not such a problem, since the wolfram wire inside will not cool down that much in 1/100 sec. You can still notice it, but the real enemy is fluorescent and non flicker free LED lights.
  • LucasAdamsonLucasAdamson
    Surely LEDs, if battery powered, are DC and hence flicker free no matter what shutter speed, right?

    I think it's fluorescent light that I am concerned about - street lights for example - pretty much unavoidable in a night-time street shoot, that I am planning. I will have to do some test then, I guess.

    It all makes me wonder why such a fuss is made about 24p/25p traditionally...I guess on film, 24p with 180 shutter is always going to be 1/48 shutter, not 1/50 like in digital, and that can cause issues for sure...
  • driftwooddriftwood
    Tell me about it. I generally use 1/100 in PAL Land but non flicker free bus lights are the bane of my life!
  • LucasAdamsonLucasAdamson
    Bus lights eh? OK, I'll look out for that. You're in Brighton right Nick? I lived there for many years. Bristol now.
  • MeierhansMeierhans
    Ah yeah, HMI (in general all lamps without a wire inside) will flicker heavy when not connected to a flickerfree power supply. Maybe we should ask local authorities to replace power supplies on all street lamps.. ;)

    @driftwood How would you decrivbe the quality difference between your new PsF modes and 24H? At 25P there should be no flicker.
  • driftwooddriftwood
    @Meierhans Did you read these?
    Panasonic has a funny way of dealing with PsF. Read this;-
    http://provideocoalition.com/index.php/atepper/story/psf8217s_missing_workflow_em_part_1_benign_psf_versus_malignant_psf/
    and more info here;- http://provideocoalition.com/index.php/atepper or http://www.allantepper.com/englishblog/
  • LucasAdamsonLucasAdamson
    I've been testing. Streetlights are flickery at over 1/100 shutter 24p, getting progressively worse as you get faster.

    What's the big deal?
  • MeierhansMeierhans
    @LucasAdamson Watch very close.. you ca get flicker on lit areas even on lower settings as well (beside 1/25 and 1/50).

    @driftwood Now I red them.. very "funny"... lets put progressive footage in an interlaced container and if this was not enough..... forget to set the interlaced flag to progressive as well. Happy guessing!
    Wondering when the first app will support "human like" interlaced detection by looking out for interlace
    artefacts in the frames.. how I hate this stupid leftover from analog times when they cheated more resolution in time & space at the same time over their limited bandwidth. Quite sure if they would have
    known how much pain this brought over mankind (well.. cutters at least) they would have trashed the resolution..
  • azza_actazza_act

    I thinking of getting a NTSC GH3 (I live in Aus) Will shooting 60p at 1/100 for slow-mo going to be an issue? Or should I wait for the PAL version.

  • charlie_orozcocharlie_orozco

    In my experience, shooting 24p with 1/50 shutter here in 50hz land doesn't remove flickering completely. I mean, flickering isn't there, but there is some sort of moving banding going slowly from top to bottom. It's very faint, but it's there. I shot using 25fps HBR and got rid of it, but although 25fps are OK with me the halved resolution HBR gives isn't. Hopefully the GH3 will be my savior in these situations! @azza_act I guess you can do that with no harm but having a little more motion blur than is desired, but will be no worse than using a 1/40 shutter, I think.

  • kavadnikavadni

    Change the ballasts out - get high frequency ballasts. You'll probably have to order them in through your lamp supplier.

    Every gaffer I have met carries a box of 50 ballasts and 50 tubes at 3200 and 50 at 5500, specifically for changing out practicals on location. They've been available since at least 1986.

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