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Old February 23rd, 2012, 12:57 PM   #1
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GH2 24p Cadence "judder"...

Hey everyone,

I am sure that it's not just me who sees the "cadence judder" on the GH2 while in 24p mode. I have tried different hacks, and it doesn't fix the problem.

I have uploaded a video which illustrates the problem pretty well. Look at the football if you don't see what I mean. Settings were 1080p24, 1/50th SS.

https://vimeo.com/37309808

Any ideas on how to combat this? Do the Canon's (5D II, 7D, T3i, etc...) have this issue?? This is an unacceptable problem. Any ideas?

Thanks,

Steven

PS: That's as smooth a pan as I have ever done, and it still looks choppy!
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Old February 23rd, 2012, 01:55 PM   #2
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Re: GH2 24p Cadence "judder"...

Do you have image stabilization switched on on the lens or in the menu?
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Old February 23rd, 2012, 04:38 PM   #3
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Re: GH2 24p Cadence "judder"...

It is on on the lens (14-140 if that matters), and when I looked to turn it off in the menu, it has three options, but none of them say that it's disabled...
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Old February 23rd, 2012, 05:19 PM   #4
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Re: GH2 24p Cadence "judder"...

I'm no expert.

What I've read, however, and and based on my limited experience:

The pan you demonstrate is at least double the speed you can go and expect a smooth pan in 24p mode.

Panning in 24pm is best done very slowly. I personally try only to pan when following a subject in 24p, when possible. When following a subject the background jitter or whatever is not noticed because the viewers eye is on the subject of the shot, not the background. You will see this in films that cost $100 million to produce. If it's shot with film, they will often have the same issues, but they shoot knowing these things.

24p requires a different shooting style than 60i or 60p, and will produce problems no matter what camera you use if you pan too quickly.
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Old February 23rd, 2012, 05:57 PM   #5
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Re: GH2 24p Cadence "judder"...

I think Jeff is exactly right.
The lens test I just posted was in Cinema mode and has the same thing.
The compression in Vimeo seems to exaggerate it.
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Old February 23rd, 2012, 09:59 PM   #6
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Re: GH2 24p Cadence "judder"...

Now that you mention that Don, I forgot that. Yes, Vimeo can be very bad that way. I've had pans that were silky smooth and shot in 60p, but they appeared jittery on Vimeo. I found I was better off giving Vimeo 60p and letting it's encoding convert it to 30p, rather than giving it 30p, seems to work better for some very strange reason.
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Old February 24th, 2012, 04:27 AM   #7
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Re: GH2 24p Cadence "judder"...

Quote:
Originally Posted by Steven Bills View Post
It is on on the lens (14-140 if that matters), and when I looked to turn it off in the menu, it has three options, but none of them say that it's disabled...
The 'Off' option on the menu is only there if there isn't an actual physical on/off switch on the lens itself, so if you're using the 14-140mm it won't be there.

Try turning off the OIS and see if that helps. The OIS on the GH2 is really for stills, or else for handheld static shots. For anything else, on this and any camera, it can produce a nasty stuttering as you move. I haven't experimented with OIS "Mode 3" which is specifically for panning - better to turn it off if your pans are smooth in the first place.
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Old February 24th, 2012, 05:04 AM   #8
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Re: GH2 24p Cadence "judder"...

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Originally Posted by Jeff Harper View Post
The pan you demonstrate is at least double the speed you can go and expect a smooth pan in 24p mode.
Samuelson's Manual For Cinematographers suggests as a guideline that the maximum panning speed at 24fps should be the speed at which it takes a static object 4 seconds to pass from one side of the screen to the other (p.314). Your pan is a little faster than that, but not by much.

Manual for cinematographers - David W. Samuelson - Google Books

This is one of the things that makes film look like film, and one of the advantages of interlaced footage (at 50i you can pan twice as fast, for example, which is very useful for sport etc.).
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Old February 24th, 2012, 05:11 AM   #9
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Re: GH2 24p Cadence "judder"...

Quote:
Originally Posted by Steven Bills View Post
Hey everyone,

I am sure that it's not just me who sees the "cadence judder" on the GH2 while in 24p mode. I have tried different hacks, and it doesn't fix the problem.

I have uploaded a video which illustrates the problem pretty well. Look at the football if you don't see what I mean. Settings were 1080p24, 1/50th SS.

https://vimeo.com/37309808

Any ideas on how to combat this? Do the Canon's (5D II, 7D, T3i, etc...) have this issue?? This is an unacceptable problem. Any ideas?

Thanks,

Steven

PS: That's as smooth a pan as I have ever done, and it still looks choppy!
Slow your pans down to 6-7 seconds to go from edge to edge and you will see an improvement.
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Old February 24th, 2012, 03:42 PM   #10
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Re: GH2 24p Cadence "judder"...

It's all about perception as well. When we watch movies we don't really think about it because we are wrapped into the story. When you shoot your own footage and edit you are more focused on analyzing the look and motion and it will stand out more that something is a little off. When everything is all put together and tells a story you will not notice it as much.
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Old February 26th, 2012, 09:26 AM   #11
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Re: GH2 24p Cadence "judder"...

I'll try experimenting with Mode 3 and let you all know how it looks.

SB
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Old February 26th, 2012, 09:50 AM   #12
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Re: GH2 24p Cadence "judder"...

Would a higher bitrate hack help combat this?
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Old February 26th, 2012, 11:45 AM   #13
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Re: GH2 24p Cadence "judder"...

No, only a higher fps would help, but then it wouldn't be 24fps any longer, it would be 60i, or 60p, or whatever frame rate you chose.

Here's a quote from the Wikepedia entry re: 24fps

"In general, 24 frames-per-second video has more trouble with fast motion than other, higher frame rates, sometimes showing a "strobe" or "choppy" motion, just like 24 frame/s film will if shot as if it's video, without careful panning, zooming, and slower camera motion. It is therefore not well-suited for programming requiring spontaneous action or "reality" camerawork.

It should also be noted that while the strobe of 24p is in many ways considered a disadvantage, it's also part of the "film look." 24 frame/s film strobes in exactly the same way." 24p - Wikipedia, the free encyclopedia

To be clear, I must qualify I have very limited experience with 24p, I've shot maybe four events in 24p, but my experience pretty much validates everything I've read on the subject, which is pretty well summed up in the above quote from the Wikipedia quote above. Motion is not handled well at all. Additionally, it seems images are softer, and obtaining manual focus using on-camera LCD seems much more difficult, but that may be a mis-perception on my part. Overall I dislike shooting with it, it's more trouble than it seems worth, but I really do like progressive as it uploads to the web so much better than interlaced without conversion to progressive.

Last edited by Jeff Harper; February 26th, 2012 at 05:29 PM.
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Old February 29th, 2012, 09:05 AM   #14
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Re: GH2 24p Cadence "judder"...

I agree with you, Jeff. It's just not something I'm use to, coming from 60i -> 30p, and then going to 24p and seeing it strobing and such. But it sounds like it's just something that we're going to have to live with, eh?

Actually, I was perusing around the internet and found an interesting article on the motion characteristics of film, and how to make the digital signal look like film.

Granted, it IS $14k, and it's a filter you drop into your matte box. And you need a genlockable camera.

Anyway.

SB
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Old February 29th, 2012, 12:40 PM   #15
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Re: GH2 24p Cadence "judder"...

Steven, I have examined threads over the last couple of years regarding 24fps, but it was the Wikipedia article that clarified things for me so much last year when I was researching the subject.

I dissed 24p in the past before ever trying it, and it so happens, that after I shot my first wedding in 24p that what I read was correct. 24fps is not ideal, by any stretch, for run and gun shooting, which is primarily what I do as a wedding shooter.

Conversely, a visit to the website for Pacific Films or any of the many other skilled shooters using 24p and it becomes clear that 24fps can and will work for run and gun, if done with the correct camera techniques. I suspect it can take a good while to master the methods needed to produce above average looking video using 24p.

I hate it, it's too soft for my taste, and too difficult for me to get a good focus, it's really distracting for me. On the other hand I've shot some decent video when I got lucky here and there using it, but I have an awful lot to learn before I can say I'm halfway proficient with it.
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