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XDCam and extreme motion blur problem

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Michael Goldberg
XDCam and extreme motion blur problem
on Feb 16, 2010 at 6:48:54 pm

Hi All,
We have a Sony XDcam PDW-F800. We shot some scenes for a commercial which are simply a man holding a box walking from right to left at a relatively slow speed. Background is green screen. We always shoot progressive for all of our fx shots, but this is the first time using this camera for this type of shot. We shot 29.97 progressive. There is an extreme motion blur on all of the shots. The ones walking across screen horizontally are tremendously bad. The shots look almost distorted. We saw this on the camera out, and the deck output in our control room. The DP tells me the shutter was set to off, and that is how they always shoot, and have never had this problem. I'm thinking this is a shutter speed problem, but he thinks different. He did a test, shooting the same scene at 29.97p, 24p, and 60i. Both progressive formats had the motion blur, and the 60i footage was clean. This is not normal motion blur, it's completely distorted and blurred footage. Can anyone explain what might be going on here?
Thanks,
Mike Goldberg


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Dave Chalmers
Re: XDCam and extreme motion blur problem
on Feb 17, 2010 at 10:53:28 am

If you are shooting progressive on a 700 I would have thought you would definitely want the shutter ON at 1/60th, otherwise you are going to have a shutter at 1/30th and will definitely get motion blur as you describe.

I think you are dead on that this is a shutter issue.

Dave


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Thomas Kist
Re: XDCam and extreme motion blur problem
on Feb 17, 2010 at 6:25:46 pm

Yes, most definitely when shooting progressive always have the shutter switched on.
For 25p I shoot with 1/50.

Thomas Kist
Freelance D.o.P
Amsterdam,The Netherlands
PDW-700,EX-3&Letus,FCP 6
http://www.thomaskist.com


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James Martin
Re: XDCam and extreme motion blur problem
on Feb 18, 2010 at 10:39:59 am

I third this as a shutter issue.

If your shutter is off, there is effectively no break between the movement, it will appear very unusual. Distinctly un-film-like.

There are a lot of DoPs who seem to use this all the time on digital cameras, I don't understand where it came from - news never shot this way, neither did TV. Only recently does it seem common.

I can understand it shooting in low light, but daylight....

Each to their own, I guess.


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dusty powers
Re: XDCam and extreme motion blur problem
on Feb 27, 2010 at 4:06:06 am

Hey Michael:

There are defined shutters for 24 (1/48th) and 30 (1/60th) frame footage to prevent excessive motion blur during pans. From what I’m hearing from you sounds as if your camera’s shutter was on and set to a shutter speed lower than what it should have been. If this was not the case then you should send your camera back to Sony and let them know it has a stuck shutter problem. Before you send it off I'd do another test and this time make sure the is off.


dusty powers
http://www.hdcrew.net



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Michael Goldberg
Re: XDCam and extreme motion blur problem
on Feb 27, 2010 at 1:57:01 pm

Hi,
The shutter was actually set to Off. From what I understand the default shutter speed (when the shutter is set to off) is 30. We're thinking this could be the culprit, although even at 30 the MB seemed excessive. We've done some more tests, still not great.

Mike



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James Martin
Re: XDCam and extreme motion blur problem
on Mar 8, 2010 at 8:40:11 pm

Hi,

I think you've just found your culprit.

General consensus is that a "standard" shutter speed is the equivalent of 180 degrees in film terms. Ie, half of your frame rate.

So, for 24 fps that's 1/48, 25 is 1/50 and 29.97/30fps its 1/60.

You said your shutter was at 1/30, which in any of these cases is going to yield significant motion blur. If you were shooting at 29.97, then 1/30 is as good as shutter off...

Your camera guy has some very serious issues with "the basics", I fear.


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Curt Pair
Re: XDCam and extreme motion blur problem
on Mar 30, 2010 at 3:16:14 am

Michael,

I would have to agree with Dave, Thomas and James. This is DEFINITELY a shutter issue. Further, at first reading the story, it almost sounded like a SLOW SHUTTER issue to me.

In actuality, it is! These guys are correct... if you aren't shooting at 1/60th, in 30p, then you're effectively shooting with a shutter speed of "half that", when the shutter is turned off, and it will result in a "slow shutter" look.

I shoot TONS of green screen work with my F800... granted I shoot mostly in 24p, but occasionally I will shoot other frame rates. To make things easy for me... I changed the shutter from "seconds to angle/degrees" and always use a "180 degree shutter angle" This eliminates any confusion and everything always works out well, no matter the frame rate selected!

Good luck, and let us know how it works out.

Curt

Curt Pair
Picture This Productions
Sony ICE Team
F900/F800/F350/PDW700/EX1/EX3/D790/D600
Adobe Premiere Pro CS3 HD/Matrox
Phoenix, AZ


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