shutter speeds faster than 1/60 in the gym

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    • #48674
      Avatarricha
      Participant

      I enjoy shooting basketball in poorly lit high school gyms. In order to freeze motion for pause or slow playback, I strive for the fastest shutter speed feasible. Recently I upgraded to the JVC GY-HM100u camera and captured some snippets using different settings. I thought I would share these results, as I am able to achieve 1/250 sec in many cases. Samples here: http://sportsflashtech.com/video/

      With a faster shutter, comes brightness & color variation, similar to the helicopter blades in a parallel posting. Light intensity and color variation occur at a 2-3 second oscillating rate. Here is a rather long sequence which shows the problem: http://www.sportsflashtech.com/tmp/Altmaier-varying_lum-and-color.avi
      The first half shows brightness oscillation. The second half shows color oscillation. The compression is not good, the image quality is poor as I just wish to illustrate the oscillation issue.
      Are there any post processing methods to deal with such brightness or color oscillation?
      My knowledge is limited, as I generally use only tmpgenc.

      Thanks! Rich

    • #199617
      AvatarAnonymous
      Inactive

      i would dare say the problem is not the camera or any post production techniques, but rather the lighting. You are dealing with the light’s wavelength against your camera’s shutter. It’s tough to get results that look like nba footage in high school gyms because they are not lit up like a professional areana.

    • #199618

      When I first read the post, I figured lack of light was culprit but after looking at the video I’m not so sure. Seems there’s plenty of light. I’m interested in hearing what others have to say.

    • #199619
      Avatarroblewis56
      Participant

      The gym lights run on 60Hz ac power so there may be some variation in brightness and color temperature at 60Hz. If your frame rate is 30fps or 60fps then there will be some synchronization. I suggest you try 24fps. Since 24 is not divisible into 60 your exposures will will not sync. with the light variation and your effect should be less.

      Robert

    • #199620
      Avatarroblewis56
      Participant

      Also there may be a bad bulb or ballast. If you can identify maybe you can get maintenance to i it.

    • #199621
      Avatarricha
      Participant

      Thanks for the comments. I am quite certain the variation is due to the fluorscent lights which naturally oscillate at 60hz, both in brightness and in color. If a shutter is slow, 1/120 or slower, then each frame gets a full cycle of variation and the scene is averaged out. If the shutter is faster than 1/120, then there is only time to capture a time fragment of the bulb going brighter and dimmer.

      Since my goal is to shoot a fast shutter, the only solutions in principle, I think, are either a) synchronize the camcorder frame to AC power (I never heard of such being possible), or b) post process to de-oscillate the light and color.

      Tonight in web searching I found this brightness variance fixing package: GBDeflicker, which may be applicable. http://www.granitebaysoftware.com/Products/ProductGBD.aspx

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