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PatrickV

GH4 jitter issue (with slider & panning)

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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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My guess is it's related to the OIS of your lens.

http://www.eoshd.com/comments/topic/7159-micro-jitter-on-panasonic-35-100-f28-when-using-power-ois/#comment-73437

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Hi Bunk,

Thanks for your response.

I checked the version number of my current lens firmware. It states Version 1.2.
This is the latest version right? Or do I have to shut my OIS off during slider/plan shots? (it's always on)

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It's just the nature of shooting at film speed (24/25p). Slow pans will have a juddery feeling because the frame rate is much slower than how we perceive motion in real life. It's the same reason why motion looks different with 30fps, 48fps, 60fps, etc.

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No this really looks like the OIS. Always turn that of when shooting really steady stuff. It will try to compensate for motion you don't want it compensating. Only use it for handheld shooting. 25p should look better then that. Give it a try and check out the results.

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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?

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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?

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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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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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By the way, when I chanced to see earlier posts, I would like to expressly state that in all my tests IS / VR was always OFF

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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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