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GH4 jitter issue (with slider & panning)


PatrickV
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Hi guys,

I noticed some jitter issues on my GH4 output today and I hope someone here can help me out. I uploaded footage (one slider shot & one pan shot) which demonstrates my issue:

Slider shot: https://vimeo.com/116564101 

Pan shot: https://vimeo.com/116564641 

Details:

Panasonic GH4
12-35mm
Shutter speed: 50
Fps: 25
Shot in 4k. Rendered in 1080p.

What do I do wrong? How can I avoid this ' jitter effect'?

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I tested it, but I didn't work out for me. I made several pans with OIS off but still the judder is noticeable. Should I use 30p for these kinds of shots, and render it as 25P?

​No, that would make it even more noticeable because youd be shooting at a faster shutter speed and then dropping frames to cut it to 25p. 

There's no solution really except to not do slow pans like that. Most films tend not to I think. Maybe you could also try filming at a slower shutter speed so that you get more motion blur?

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Ok. But fast or slow pans: in both situations the judder is noticeable. Also when filming fast moving subjects like cars the judder is noticeable. 
I use Kingston SDXC Professional UHS-I U3 64GB cards (read: 90mb/s write: 80 mb/s). Are these fast enough?

​Patrick you are not reading the answers. There is no fault or problem. Recording 24p/25p there is "judder" when things or the camera moves. Have you ever watched a motion picture in theater?? 

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​Patrick you are not reading the answers. There is no fault or problem. Recording 24p/25p there is "judder" when things or the camera moves. Have you ever watched a motion picture in theater?? 

​You are forgetting that the footage is being watched on a monitor that refreshes at 60Hz. Something shot at 24Hz is not going to mesh well with that.

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  • 1 year later...

I faced similar issues with GH4; jarring motion / judder when panned at 25p.

Test A: The situation seemed to get better (for good) - i meant lesser judder at 50p (of coarse the shutter speed had to be increase - Ts <= 1/00s) but the problem still remained.

Test B: The next step was to enable the variable frame rate to 75fps and consequently I also set the shutter speed to 1/320 s (~ 1/4 times the frame length) and panned it slowly enough to reduce the judder and it did reduce the judder. Well, in the final edit I increased the speed to 200% of the original footage to get something decent (subjective).

Conclusion: By the way, while test A produced a unacceptable video but contained the background audio; Test B produced an acceptable video with no audio (something that is stated to be common when VFR is ON).

I believe this video judder is either a

mechanical problem: Owing to the use of (slow) rolling shutter

OR

codec issue and I can't comprehend this.

By the way EOS 7d with similar settings i.e.(Full HD 25p) produced no judder when panned at the same angular velocity!

My work around: 

USE  GH4 sparingly for tilt / pan. For a linear slide application it might still be useful as the frame traversed is not going to get amplified with distance as is with a pan, keeping the velocity invariant with respect to the distance.

USE EOS 7D with glee:)

Overall, I am still discovering the drawbacks of GH4 although I see some definitive advantages with it...Time for a serious upgrade by Panasonic / bug fix...

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try using correct shutter speeds which allow motion blur to smooth the transition from each frame.  You should stick to the 180 degree rule or shutter speed = double your frame rate. Shooting at 75fps / 1/320 is not going to help you. 

 

I like the fact that we are here to support each other but sometimes I wonder how so many "film makers"  have invested in all the gear but not understand the fundamental underlying basics of film / video.

if your camera is really moving around  and you want to smooth out the motion you can go to shutter speed = frame rate  - a neat trick that really helps smooth out video - but gives you some excessive motion blur. 

 

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