Question re: Rolling Shutter

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James McDonagh

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Question re: Rolling Shutter

PostFri Apr 13, 2018 4:20 pm

Hey guys,

I was doing some filming for my portfolio yesterday and I decided to go into a Cathedral to get some footage and when I looked back the video files I was absolutely horrified to see how much "jelo" I was getting as a panned my camera. At one stage the jelo/rolling shutter affect was so bad I was convinced I had damaged my camera in some way. I've always been aware of the problems of panning with the URSA Mini Pro but I had never seen it as bad as yesterday.

However, upon examining my footage closer I realized that the main issue that was causing the jelo/tearing affect was high contrast of light and dark in the same image as a panned. For example, in the video below, in the first clip you can see immense tearing as that's where this high contrast of light comes into play whereas in the second clip of the video there is even lighting and as such there is no tearing. Also, the fact that the second clip was taken after the first gave me the assurance that I didn't damage the camera while shooting!

Could anyone please elaborate on why the high contrast of light and dark leads to shutter tearing and what precautions to take to make sure that this won't happen? It seems to me that the only sure way of knowing whether or not you're getting jelo-tearing while panning is to tilt slowly outdoors where the lighting is even.

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Denny Smith

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Re: Question re: Rolling Shutter

PostFri Apr 13, 2018 4:36 pm

Did not look that bad, most obvious were the quick jerky movements, which will reveal RS artifacts. Yiu need to make slower, more deliberate pans and camera movements, some of,yours were just too quick, and this makes them distracting. Also I think the low light added to your problems here. Even shooting film, your quick movements would have caused issues.

Try slowing down, take a deep breath and learn how to control yiur camers with your body. Do a search on cine panning techniques, you need to wind yiur body in the opposite direction of the pan, so yiumuse yiur unwinding motion to smoothly and slowly pan the camera.

Also your tripod head seems not up to the task of holding your camera steady, not sure if it this or poor technique. Can you set your camera to a 10-25 degree tilt and let go, and have the head hold the rig in place without tipping up,or down? If not, there is part of your problem.
Cheers
Denny Smith
SHA Productions
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James McDonagh

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Re: Question re: Rolling Shutter

PostFri Apr 13, 2018 5:53 pm

Denny Smith wrote:Did not look that bad, most obvious were the quick jerky movements, which will reveal RS artifacts. Yiu need to make slower, more deliberate pans and camera movements, some of,yours were just too quick, and this makes them distracting. Also I think the low light added to your problems here. Even shooting film, your quick movements would have caused issues.

Try slowing down, take a deep breath and learn how to control yiur camers with your body. Do a search on cine panning techniques, you need to wind yiur body in the opposite direction of the pan, so yiumuse yiur unwinding motion to smoothly and slowly pan the camera.

Also your tripod head seems not up to the task of holding your camera steady, not sure if it this or poor technique. Can you set your camera to a 10-25 degree tilt and let go, and have the head hold the rig in place without tipping up,or down? If not, there is part of your problem.
Cheers


Hi Denny, thank you for the advice. Did you look at the video on Vimeo.com in full screen mode? The stutter is more noticeable then.

And to answer your question: yes, it can, it can even hold it perfectly steady at severe angles such as 70/80 degrees. I should work on my technique more.
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Denny Smith

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Re: Question re: Rolling Shutter

PostFri Apr 13, 2018 6:01 pm

Good, what video head are you using on the tripod? Sounds like it is up to the job. Yes, I would work on your technique, good camera movements takes lots of practice. Good luck
Cheers
Last edited by Denny Smith on Fri Apr 13, 2018 10:12 pm, edited 1 time in total.
Denny Smith
SHA Productions
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James McDonagh

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Re: Question re: Rolling Shutter

PostFri Apr 13, 2018 9:57 pm

Denny Smith wrote:Good, what videomhesd are you using? Sounds like it is up to the job. Yes, I would work on your technique, good camera movements takes lots of practice. Good luck
Cheers


videomhsed???

Also, did you watch the video in full screen to see the jitter?
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Denny Smith

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Re: Question re: Rolling Shutter

PostFri Apr 13, 2018 10:14 pm

Yes, looks like you are paning too fast, and not always smoothly. Think of dancing a slow waltz with a fragile young woman... :roll:
I meant Video Head on the tripod.
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Denny Smith
SHA Productions
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Robert Niessner

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Re: Question re: Rolling Shutter

PostFri Apr 13, 2018 11:33 pm

I've watched you sample clip now several times full screen on my iPad Pro (the new one with 120Hz screen). There is no trace of rolling shutter jello - which would visibly bend straight lines. The UMP has a very fast readout.

What you see at the high contrast area of the window is pretty normal for panning too fast. If you skim through the video frame by frame you can see that there is no tearing at the window. It is a jumpy trace effect made up by your eyes and brain because the high contrast areas jump a lot of pixels per frame.
This is a temporal effect which can be reduced by slower panning and/or increasing the recording framerate.
Robert Niessner
LAUFBILDkommission
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Denny Smith

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Re: Question re: Rolling Shutter

PostSat Apr 14, 2018 1:35 am

That was my take too Robert
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Denny Smith
SHA Productions
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Chad Capeland

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Re: Question re: Rolling Shutter

PostSat Apr 14, 2018 1:52 am

I don't see it. Judder, though? Yes. Increase your framerate and shutter angle and see if it alleviates the issue.
Chad Capeland
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James McDonagh

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Re: Question re: Rolling Shutter

PostSun Apr 15, 2018 3:10 pm

Robert Niessner wrote:I've watched you sample clip now several times full screen on my iPad Pro (the new one with 120Hz screen). There is no trace of rolling shutter jello - which would visibly bend straight lines. The UMP has a very fast readout.

What you see at the high contrast area of the window is pretty normal for panning too fast. If you skim through the video frame by frame you can see that there is no tearing at the window. It is a jumpy trace effect made up by your eyes and brain because the high contrast areas jump a lot of pixels per frame.
This is a temporal effect which can be reduced by slower panning and/or increasing the recording framerate.


I think this may actually be more to do with my laptop monitor rather than the mini pro!! After watching the footage on my iPhone there is very little jitter, although I'm not sure how much that has to do with the difference in monitor size. My laptop screen is only 60hz, could this be the issue do you think?
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Robert Niessner

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Re: Question re: Rolling Shutter

PostThu Apr 26, 2018 5:05 pm

James McDonagh wrote:I think this may actually be more to do with my laptop monitor rather than the mini pro!! After watching the footage on my iPhone there is very little jitter, although I'm not sure how much that has to do with the difference in monitor size. My laptop screen is only 60hz, could this be the issue do you think?


Some video player on PCs do indeed have a problem with synchronized playback and that can lead to tearing, yes.
Robert Niessner
LAUFBILDkommission
Graz / Austria
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Read the blog in English via Google Translate:
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Stu Aitken

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Re: Question re: Rolling Shutter

PostThu Apr 26, 2018 11:17 pm

if your on windows 7 make sure you have an 'aero' theme active on your display settings to avid video tearing and v-sync issues

its not at all explicit but running a non-aero theme for some reason disables certain performance settings under the hood (and annoyingly if your running low on system graphic resources windows itself will often recommend that you turn aero off or similar)

not sure if they fixed all that crap in win10 or not

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