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Shutter speed is Effecting my frame Rate GH2
  • iwillvfxiwillvfx

    Hey everyone, not so much a beginner when it comes to hacking anymore, but for reason I cannot understand why camera is acting this way.

    I'm a huge fan of the 720p 60fps modes that this camera has after the hacks, and for some reason recently I'm noticing that in this mode, I am not producing 60 frames per second. I usually shoot in 2 modes, 24p cinema mode for 24fps at 1080. And then in Manual Mode 720p avchd which should give me 60fps.

    I've seemed to have pin pointed the cause and it seems to be related to shutter speed. When I should below 1/60th of a second on the shutter, I get less than 60fps, it's almost as if it's shooting 30 frames per second.

    This is really frustrating cause I don't believe it ever did that before. Why would changing your shutter angle change the frames per second.

    Any help to fix this would be helpful.

    Thanks

  • 6 Replies sorted by
  • arknoxarknox

    When you shoot at 720p 60 with a shutter lower than 1/60 the camera will always drop the frame rate.

    It is physically impossible to have a shutter speed lower than your frame rate.

  • iwillvfxiwillvfx

    Firstly, thank you for such a fast reply,

    I could have sworn this wasn't the case. but I suppose that make perfect sense. I went to film school and this stuff still confuses me. So what is the resulting frames rates that I can expect by shooting below 1/60. If I shoot 1/30 am i effectively shooting 30 fps? Thanks

  • htinlahtinla

    it's still 60fps, but every 1/30 sec exposure will cover two frames.

  • iwillvfxiwillvfx

    So in the same way as film cameras of old could capture 1/24/ or 1/48th of a second, when shooting on 24p cinema mode on the Gh2, because there is no 1/24 shutter speed, the minimum to not drop frames is 1/25 or 1/30th correct? Cause anything below 1/25 whould drop frames?

    Also, could one use this in some ways to shoot a 25 fps at 720avchd mode keeping in mind that you would be limiting yourself just to get a frame rate at a desirable resolution of 720p?

    Thanks

  • iwillvfxiwillvfx

    @htinla, so effectively is capturing 2 frames, that are somewhat identical?

    Thank you

  • edwardmedwardm

    On my old Panasonic AG-DVC30 standard def camera, it's 30 frame "progressive" mode was a fake progressive mode that had less resolution than its 60i mode. A simple way to create a true 30p image was to shoot in 60i at 1/30 of second. That would expose both interleaved half frames to the same image - worked great as long as you had slow moving subjects.

    This is likely the case with the GH-2 (haven't tried this there). Take it to an extreme, let's say, you shoot with a 1/4th second shutter, the maximum number of images you could take would be 4 per second. It doesn't matter whether you are shooting at 24p, 25p, 30p or 60p - there are still only 4 separate images being exposed per second.

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