Please help with FPS and AV settings

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    • #90716
      Avatardon_lemur
      Member

      Hi!
      I want to shoot a promotional video of bicycle wheel lights which show a stable picture on the spokes when the wheel is turning.
      Now I am facing the problem that the frequencies of the LEDs and the camcorder frequency are similar and thus I get some “blank” segments in the video.
      What I tried is to shoot the video and change the settings on an iPhone 6, Samsung S7 an action cam and a Canon 1000D.
      The best result I received on the Samsung phone with the following video settings:
      – ISO 100
      – exposition (EV) +2
      – frame rate 30 FPS

      Here is the result (with a wheel turning speed of 20-25 km/h):

      And here is how it should be:

      Could you help me with the settings? What do I need to change to get a blank-free picture?

      Michael

    • #214151
      AvatarJackWolcott
      Participant

      Just a guess, but I would think it necessary for the shutter speed to fairly closely match the RPM of the wheel.

      Back in the day, when video monitors were CRT, we would shoot at a 60th of a second or faster to match the scan rate of the monitor to avoid rollover. I believe you have the same problem/solution here.

    • #214157
      AvatarKevin Mc
      Member

      Just popped in to suggest using a camcorder that can capture at 60 FPS, but Jack beat me to it. But even so, you might even require a higher FPS rate. A GoPro Hero4 can shoot as high as 240 FPS, and is reasonably priced. Might be a good platform to use, as it would give you several high frame rate options to test until you find just the right setting.

    • #214158
      Avatardon_lemur
      Member

      Jack and Kevin, thanks for the answers!
      I tried it with 60 FPS but it was not better compared to 30 FPS…
      The manufacturer of the LEDs informed me that they used an iPhone 6 with a “professional camcorder” App and the result was even better than in the promotional video above.
      Well, I tried a similar App on my Samsung S7 but didn’t get the result.

    • #214160
      AvatarKevin Mc
      Member

      Bummer :(… I’m thinking that 120 or 240 FPS would help, as they are more likely to catch frames of the LED light cycles (Hz / refresh rate), that slower shutter speeds are missing. See if *anyone you know* has a GoPro Hero4, and give it a try before buying anything – just to find out if more FPS of video fixes your problem.

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