Thread: Shaky distortion when panning

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  1. #1 Shaky distortion when panning 
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    Hi everyone, I like to get your help on this. This very short test clip was shot with a C200 in 4K DCI at 23.976 frame rate. We want to keep it at that resolution and frame rate. Shutter angle was at 180, ISO at 800. But as the camera pans, there is such a motion distortion or jerkiness to it. I don't see any skip frames too. I think it is more than motion blur. What could be the cause of this?


    https://1drv.ms/v/s!Agvdi7GDhv1_hLgMF0K4vYNOYQDXfA
    Last edited by EYu; 03-05-2018 at 03:36 PM.
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  2. #2  
    Senior Member LochnessDigital's Avatar
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    Looks like pan judder to me. You panned quite a bit on a 50mm in like 4 seconds. There's charts and calculators you can find out there that will give you an idea how slow your pans should be for a given sensor size, focal length, and framerate.
    Aaron Lochert
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  3. #3  
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    Quote Originally Posted by LochnessDigital View Post
    Looks like pan judder to me. You panned quite a bit on a 50mm in like 4 seconds. There's charts and calculators you can find out there that will give you an idea how slow your pans should be for a given sensor size, focal length, and framerate.
    Thanks. Was able to find a few articles on it.
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  4. #4  
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    Gotta love how RED has so much useful information on their site!

    I did think it was odd though that the clip is mostly smooth except what looks like only two frame jumps. Makes me think something else could be involved. Dropped frame without telling you maybe? It's not a constant judder. I've had this happen on my micro cinema camera, where some takes did not have the issue, some did. Sometimes it was reported by the camera, sometimes it wasnt.
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  5. #5  
    Senior Member LochnessDigital's Avatar
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    Quote Originally Posted by GeranSimpson View Post
    Gotta love how RED has so much useful information on their site!

    I did think it was odd though that the clip is mostly smooth except what looks like only two frame jumps. Makes me think something else could be involved. Dropped frame without telling you maybe? It's not a constant judder. I've had this happen on my micro cinema camera, where some takes did not have the issue, some did. Sometimes it was reported by the camera, sometimes it wasnt.
    When I played the clip in the browser, I got what looked like a repeatable frame-drop but after I downloaded the file it played smoothly, although there is still pan judder present.

    Best to download the clip and view in a video player rather than in an internet browser.
    Aaron Lochert
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  6. #6  
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    The 7 second rule or thumb does the trick. However not all pan can be that slow. Also, why is it that there are no visible judder when shooting video with a DSLR? I tried the same with a DSLR - (Panny G7). I was fast panning the DSLR too. Does it have to do with the sensor size too?
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  7. #7  
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    EYu, not all rolling shutters are created equal, and they all have different sensor readout times, which will effect any RS artifacts, like jitter in fast pans. The C200 probably has a much s,owner sensor readout time than the Panny csmera, also smaller sensors with bigger photosites will have faster readout times as a rule, which is why you can over rank a Panny GH5/s faster at a given fps has a slower readout time than a camers with the same or similar size sensor that can do 4K 60fps.

    Bigger sensors like S35 sensors in BM and Canon cameras switch to a window mode, using fewer photosites, to increase the sensor readout time to get faster frame rstes. So yes, the sensor size has a lot to do with the RS artifacts, as larger, higher resolution sensors tend to have slower readout times.
    Cheers
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  8. #8  
    Senior Member jambredz's Avatar
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    Looks pretty normal to me for that speed of panning on a 50. Pan slower
    Darren Scott
    Freelance Director/Director of Photography


    https://vimeo.com/jambredzvisions/videos
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