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Canon 7D problem even with slow PAN's (so it's not rolling shutter?)

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Osku Petteri
Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 5, 2010 at 3:39:00 pm

Hey,



I have this annoiyng problem with Canon 7D. Please check it out, it's only a few seconds of video.

http://reels.creativecow.net/film/rolling-shutter-problem-canon-7d

I always thought it's the rolling shutter, but it's more like jumpy, blinky stuff this problems, and it should not be the rolling shutter since it's really slow pans ( sideways movements )

If it's not rolling shutter problem then what is it?


Shot with Canon 7D
1080P 25p Shutter speed 1/50
1.shot - Really slow movement sideways, no speed changes
2.shot - Really slow Pan speeded up a little bit in FCP

First shot - The object is blinking, it doesn't run smoothly...
You can see the metal parts blinking quite annoyingly in the second shot

Is these because of the Rolling Shutter??
Everybody always complains because of the jelloying of the pictures. So these are not harsh movements, but there is still this annoying effect in the shots, how can i fix it in post / avoid it when shooting?


Thanks everyone!



-Osku Petteri-


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Michael Locke
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 5, 2010 at 7:02:26 pm

Hello Osku,
Since panning is a physical movement of he camera, one must ask how you moved it. The footage suggests the physical is the problem (uneven side-to-side speed). "Blinking" I think of as a change in light/appearance intensity, so I'm not sure what you mean there. The picture integrity seems fine, but I got this effect trying to pan a landscape by twisting clockwise on a monopod with no fluid head (not so good). The smoothe-cam filter in Final Cut works pretty good for single-axis (horizontal) variation; anything more complicated (bumpy car ride) http://library.creativecow.net/anderson_iain/Coremelt_Lock-and-Load-Express... looks good. Hope this helps...ML


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Adam Duplay
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 5, 2010 at 10:44:46 pm

Did you have the lens image stabilizer switched on? That should be off when shooting from a tripod.

Adam Duplay


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Osku Petteri
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 6, 2010 at 7:24:18 pm

Thanks for quick answers!


Lenses used:

Tokina 11-16 2.8 no image stabilizer
Sigma 17-50 2.8 no image stabilizer


Yes saying it's blinking is not the right term but the problem is real and I don't know the term if it's not rolling shutter related.

Smooth Cam in FCP won't help here. Or in Motion.


Other succestions?


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Bob Dix
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 5, 2010 at 11:42:49 pm

The 5D similar to the 7D records at about 38.5Mbps , make sure your CF card is UDMA and about 45Mbps, we use Sandisk Extreme 4 or 60Mbps , it may help ?

Freelance Imaging & Video
AUSTRALIA


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Osku Petteri
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 6, 2010 at 7:25:25 pm

Card used Sandisk Extreme 3 32gigs, the bitrate should be enough.


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Bob Dix
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 7, 2010 at 7:38:28 am

That is slower than the camera. Ultra does not cut it ?

Freelance Imaging & Video
AUSTRALIA


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Alf Hanna
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 9, 2010 at 4:16:45 pm

can you do some tests of similar situations at various shutter speeds? It would have been helpful to see if you could reproduce this same thing at 30fps and higher. I try to shoot at 30 fps or higher when I anticipate more camera movement.
What kind of mount were you on?
Was the mount moving totally fluidly?

Alf


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Todd Terry
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 9, 2010 at 4:42:46 pm

[Alf Hanna] "do some tests of similar situations at various shutter speeds... see if you could reproduce this same thing at 30fps and higher."

That's a little confusing. "30fps" is a frame rate, not a shutter speed. Frame rates and shutter speeds are two entirely different things.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Alf Hanna
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 9, 2010 at 7:44:47 pm

message deleted...


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Alf Hanna
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 9, 2010 at 7:56:51 pm

From Wikip. This gets at what I think I'm trying to say here..am I wrong in this? Trying 30 fps might be smoother than 24?

"Judder is a real problem in this day where 46 and 52-inch (1,300 mm) television sets have become the norm. The amount an object moves between frames physically on screen is now of such a magnitude that objects and backgrounds can no longer be classed as "clear". Letters cannot be read and looking at vertical objects like trees and lamp posts while the camera is panning sideways have even been known to cause headaches. The actual amount of motion blur needed to make 24 frames per second smooth eliminates every remnant of detail from the frames. Where adding the right amount of motion blur eliminates the uncomfortable side effects, it is more than often simply not done. It requires extra processing to turn the extra frames of a 120 frame/s source (which is the current recording "standard"[citation needed]) into adequate motion blur for a 24 frame/s target. It would also potentially remove the detail and clarity of background advertising. Today, devices are up to the task of displaying 60 frames per second, using them all on the source media is very much possible. For example, the amount of data that can be stored on blu-ray and the processing power to decode it is more than adequate. Though the extra frames when not filtered correctly, can produce a somewhat video-esque quality to the whole, the improvement to motion heavy sequences is undeniable. Televisions these days often have an option to do some kind of frame interpolation (what would be a frame between 2 real frames gets calculated to some degree), where for frames that are almost identical this can give some manner of improvement in judder, it comes nowhere close to a source having a higher number of frames, it is merely a trick to compensate for sources not having a high enough FPS rate. This interpolation creates artifacts on screen that are clearly noticeable also."

Alf


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Todd Terry
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 9, 2010 at 8:21:32 pm

If anyone has ever watched an feature film on one of these new displays that "help" the viewer by interpolating "missing" frames you'll quickly see the problem... it looks like crap. Buy one if you want to see a $50 million dollar feature film look like a home movie. It's horrible.

"can produce a somewhat video-esque quality to the whole, the improvement to motion heavy sequences is undeniable"

Depends on what you think "improvement" is, I guess. Making footage look more like video and making action sequences look like instant TV news footage wouldn't be considered an improvement by most filmmakers.

I finally got around to looking at the footage in question from the first post. That is not a rolling shutter issue. That is a frames issue. I'm assuming from your specs that the footage is 25fps and you are actually using it on a 25fps timeline as well. If there is an inconsistency in those two, you will have that kind of problem. The second shot is likely exhibiting problems because you said it was "speeded up a little bit in FCP." That can be a big problem. Unless you are changing the speed by an exact multiple of the main timeline (such as doubling it, or halving it) you can run into problems because it can no longer be displayed frame-for-frame. By increasing its speed "a little" (we don't know by what amount), your NLE is having to drop frames here and there to account for the time difference... thus giving you the jerky movement. I don't know about FCP, but in Premiere you can turn on the "Frame Blending" feature for shots that are not at 100% speed which helps some.

As to one comment that was deleted... no, shutter speeds and frame rates are not constant. A "normal" shutter speed is considered that speed which would be equivalent to a 180° shutter in a film camera. I.e., if your frame rate is 24fps, a "normal" shutter would be 1/48th of a second. If your frame rate is 30fps, a "normal" shutter would be 1/60th. But they don't have to be... they can be faster or slower than "normal" with the decision made for aesthetic (or for exposure) reasons. Often action sequences (the most frequent example) are shot with higher shutter speeds to freeze the action in each frame and make the scene look...well... more "actiony." See Saving Private Ryan to see this done well. See Gladiator to see this done waaaaaay over the top.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Alf Hanna
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 9, 2010 at 9:11:26 pm

Thanks Terry, I removed my post on that for that very reason. Easy to post without giving it enough thought. I so rarely think about changing the shutter when I shift to a faster FPS.

I didn't catch his discussion about speeding it up a bit in FCP, I thought that was what he did to 'fix' the problem that already was there.

Anyway, thanks for that post, it's a good learning point to remember for those of us that haven't used a fully manual movie camera in decades!

Alf


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Osku Petteri
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 21, 2010 at 11:15:35 pm

Hello and many thanks for the answers,


I've been on a vacation and just got back.


QUOTE:
That is not a rolling shutter issue. That is a frames issue. I'm assuming from your specs that the footage is 25fps and you are actually using it on a 25fps timeline as well. If there is an inconsistency in those two, you will have that kind of problem. The second shot is likely exhibiting problems because you said it was "speeded up a little bit in FCP." That can be a big problem. Unless you are changing the speed by an exact multiple of the main timeline (such as doubling it, or halving it) you can run into problems because it can no longer be displayed frame-for-frame. By increasing its speed "a little" (we don't know by what amount), your NLE is having to drop frames here and there to account for the time difference... thus giving you the jerky movement. I don't know about FCP, but in Premiere you can turn on the "Frame Blending" feature for shots that are not at 100% speed which helps some.

I am quite sure the issue was there before. It could be seen when watching the raw material. Yes Final Cut also has frame blending but it is usually really crap since it looks like it's just blurring half of the frames in between.

Correct it was 25fps on a 25fps timeline.

Actually what i'm gonna do is go back to the material and check it without the speed changes. I'll get back to you cause that seems quite reasonable solution.


Thanks guys,

-Osku-


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Osku Petteri
Re: Canon 7D problem even with slow PAN's (so it's not rolling shutter?)
on Nov 21, 2010 at 11:31:51 pm

Are you sure about this? 7D Manual says that for VIDEO your card should do at least 8MB/sec read and write.

-Osku


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