Rolling Shutter an Issue if Subject Moves but Camera Doesn't? at DVinfo.net

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Old May 8th, 2007, 12:46 AM   #1
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Rolling Shutter an Issue if Subject Moves but Camera Doesn't?

Does camera movement or subject movement cause image displacement due to rolling shutter?

I will be filming fast moving subjects at high shutter speeds. However, the camera itself will be stationary and mounted on a tripod.

Since the camera will be fixed and not paning, dollying, etc. will rolling shutter still be an issue?

Thanks much!
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Old May 8th, 2007, 01:27 AM   #2
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My experiences with are always with panning and tilting.
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Old May 8th, 2007, 01:49 AM   #3
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rolling shutter is a problem is subject filmed move sufficiently fast in the frame.
this can be caused by subject or camera movement.
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Old May 8th, 2007, 02:13 AM   #4
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I havent seen a lot of rolling shutter artifacting. I am fairly familiar with the look of a rolling shutter, and so far I dont judge the hv20 to exhibit all that much rolling shutter artifacting. Doesnt seem much worse than say SI-2k or RED. But then i havent really tested the hv20 as much as i would like yet. maybe im just being optimistic. I was not able to create noticeable skew or compression/expansion in fast pans/tilts that were visible in the builtin LCD.
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Old May 8th, 2007, 02:57 AM   #5
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Quote:
Originally Posted by Noah Yuan-Vogel View Post
I was not able to create noticeable skew or compression/expansion in fast pans/tilts that were visible in the builtin LCD.
It's very easy to see if you use 25p or 24p mode. That's because a single frame in a 50i/60i image doesn't last as long and it's harder to spot the bending. The clips that have been posted show the same amount of rolling as the hc1/hv10.

If you're filming high speed objects with a high speed shutter then I'd advise you to look at regular ccd cams.
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Old May 8th, 2007, 08:19 AM   #6
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That's odd, in my experience rolling shutter artifacts become more noticeable with lower framerates since they the artifacts are closely tied with the length of the readout time of the sensor which is directly related to the length of the frame. Slower framerate = longer frametime = greater time difference between top and bottom lines = greater skew. But then who knows how the sensor is clocked in different modes.
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Old May 8th, 2007, 09:46 AM   #7
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Quote:
Originally Posted by Noah Yuan-Vogel View Post
I havent seen a lot of rolling shutter artifacting. I am fairly familiar with the look of a rolling shutter, and so far I dont judge the hv20 to exhibit all that much rolling shutter artifacting. Doesnt seem much worse than say SI-2k or RED. But then i havent really tested the hv20 as much as i would like yet. maybe im just being optimistic. I was not able to create noticeable skew or compression/expansion in fast pans/tilts that were visible in the builtin LCD.

Noah:

Can you describe rolling shutter artifact more.

My issues involved slow pans and tilts. I had a gravestone forground I was focused on. I did have AIF on, because I wanted camera to change focus as I panned to right and up to focus on more graves stones in distance. Gravestone in foreground started to pulse, and the lettering on front seemed to almost float in front of stone.

On another pan, I also had a similar problem with a tree trunk that seemed to jump slightly during the pan, whether right or left. There was running creek in background.

In another shot, I pan up to a wood sided covered bridge. The boards seem to be dancing on the side of the bridge.

All this was shot in 24p. I was using 1/48 shutter speed on most. The tree situation occurred in Cinemode too, if I recall.

OIS may have been on, which I understand also could create an issue. But this seems different that an OIS issue.


I will post small clips on Megauploads this evening if someone want to see them.
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Old May 8th, 2007, 10:21 AM   #8
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Those dont sound like they are related to the rolling shutter. Are you doing an inverse pulldown to get real 24p or are you just watching the 24p that still has the pulldown applied? the pulsing problem sounds like an autofocus hunting problem.
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Old May 8th, 2007, 10:27 AM   #9
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Is "rolling shutter" the same as the diagonal sheering of the image we're all seeing as the result of CMOS processing on fast/shakey camera moves? If so, and if that's what the OP was referring to, I see it only on camera movement - not subject movement. And I only see it when I shoot handheld and I shake the camera by walking and shooting or just b/c I'm a shakey guy at times. When the camera is mounted on a tripod/monopod, even reasonably fast pans look fine to me. And like I said, subject movement looks the same as my (now ex) DVX100. BTW - I'm shooting exclusively 24p.
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Old May 8th, 2007, 11:29 AM   #10
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Yeah, same thing. Although it shouldn't matter whether the subject or the camera is moving, just the rate at which the subject traverses the screen relative to the camera. It may only be more noticeable on camera movement because camera moving the camera creates faster screen movements than most subjects can create.
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Old May 8th, 2007, 12:15 PM   #11
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Quote:
Originally Posted by Mikko Lopponen View Post
It's very easy to see if you use 25p or 24p mode. That's because a single frame in a 50i/60i image doesn't last as long and it's harder to spot the bending. The clips that have been posted show the same amount of rolling as the hc1/hv10.

If you're filming high speed objects with a high speed shutter then I'd advise you to look at regular ccd cams.
Mikko, my plan is to shoot at 60i and then detinterlace to 60p. I believe Vegas can accomplish this (don't think Xpress Pro can).

One camera option is the Panasonic GS320. It's 3CCD and also has a much faster max shutter speed: 1/8000th vs 1/2000. But its resolution is only 720 by 480 in either 4:3 or 16:9.

I'm just concerned about the lower resolution, esp. since I'll be de-interlacing.
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Old May 8th, 2007, 02:44 PM   #12
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Quote:
Originally Posted by Noah Yuan-Vogel View Post
Those dont sound like they are related to the rolling shutter. Are you doing an inverse pulldown to get real 24p or are you just watching the 24p that still has the pulldown applied? the pulsing problem sounds like an autofocus hunting problem.
Noah

No pull down at all. Neither Premiere or Vegas support that at present.

Here is a clip of about 50 mgbyte (.m2v) which demonstrates issue on 3 differents scenes. I'd like someone to look at it and tell me if problem is the rolling shutter. Please right click and save target.

http://www.makeyourfilm.net/downloads/HV20shot.m2v
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Old May 8th, 2007, 03:52 PM   #13
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Chris, do you mean "no inverse pulldown at all"? The footage looks like 24p@60i footage with pulldown was taken right off the camera. I think its just that the hybrid frames look blurry in comparison to the progressive ones. I'll be able to see better when i view it at home where i have monitor that can display 1080.
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Old May 8th, 2007, 03:55 PM   #14
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Originally Posted by Peter J Alessandria View Post
If so, and if that's what the OP was referring to, I see it only on camera movement - not subject movement.
I did a fight scene recently and a lot of the movements had some strange bendiness. Frenetic action is a bit harder to do, although not impossible.
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Old May 8th, 2007, 04:02 PM   #15
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Originally Posted by Chris Barcellos View Post
I'd like someone to look at it and tell me if problem is the rolling shutter.
Definitely not. Looks like a pull-down deinterlacing issue.
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