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EX3 and rolling scan lines

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Kris Anderson
EX3 and rolling scan lines
on Mar 10, 2009 at 6:32:03 am

I recently shot a live concert with an EX3 as well as an HPX-3000. I was gathering some overaly, so this wasn't part of a live switch at all. The pics from the HPX look AMAZING but I'm noticing that the pics from the EX3 have a sort of rolling scan line going through them that was NOT evident on the LCD screen. The camera was set to 1920x1080 in HQ mode. I was shooting in NZ so we were on 220v/50hz power. I'm really bummed as it renders a lot of shots absolutely useless and the shoot cost me a small fortune.

I've compressed it down for anyone to take a look at... here's the link:

http://files.me.com/musikwerks/268lzu.mov

The password is: sonytest

It's particularly noticeable when the white light swings by the drummer on the left of frame.

If this is not a camera fault, but the way the EX3 handles these kinds of images then Sony just lost me forever. Very disappointed.


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Michael Slowe
Re: EX3 and rolling scan lines
on Mar 10, 2009 at 8:51:02 am

Sorry chum, that's the CMOS as opposed to the good old chips. A wedding videographer I know finds it impossible to use the EX1 because the stills photographer using flash makes the video useless with the same problem that you have. There have been numerous posts on this forum about it. So far I've seen nothing from Sony on the subject.

Michael Slowe


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john sharaf
Re: EX3 and rolling scan lines
on Mar 10, 2009 at 3:34:56 pm

Yeah, definitely rolling shutter from CMOS imager; a very good example! Of all the cases that you'll see it though, in a rock video with moving lights you can almost get away with it. I predict you'll use the footage here (because you have to) and are more careful in the future not to use a CMOS camera (think Red) when you might encounter similar problems. No one tool is appropriate for all conditions; the skilled camera person these days must possess a myriad knowledge base so as not to get "snookered" buy their chosen technology. Of course the best result of your problem with this shoot is that you are now an expert on CMOS rolling shutter effect and by sharing with us may have saved others from repeating your problem. Thanks!

JS



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Kris Anderson
Re: EX3 and rolling scan lines
on Mar 10, 2009 at 8:50:15 pm

Thanks guys. As you may have surmised, I'm not a 'skilled cameraperson'! which is why I had the EX3 and the HPX3000 went with someone who knew what they were doing!

I found this on wikipedia....

Like many CMOS-based cameras, images captured by the Red One show rolling shutter artifacts. These occur because data is read from the sensor line by line over a short period of time, rather than all at once, so each frame in an image sequence does not actually represent a single instant in time.


And it's a real concern because the next phase of this project is a multi-camera Red shoot. I'm now re-thinking that and will have to talk it over with the DP. I may get away with it as it's a controlled lighting environment but it's definitely been an eye opener.



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Brian Barkley
Re: EX3 and rolling scan lines
on Mar 10, 2009 at 9:23:37 pm

I wonder if shooting in NZ with 25 fps or 50 fps would have solved your problem? Were you shooting AC or battery? The AC at the concert might best have been matched with 25 fps or 50 fps.




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Kris Anderson
Re: EX3 and rolling scan lines
on Mar 10, 2009 at 9:48:17 pm

Hi Brian... I was shooting off battery at 1080 50i in HQ mode (35mb/s).


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Bruce Rawlings
Re: EX3 and rolling scan lines
on Mar 12, 2009 at 7:33:37 am

Were you shooting in PAL or NTSC mode?



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Kris Anderson
Re: EX3 and rolling scan lines
on Mar 12, 2009 at 8:10:59 am

Shooting 1080, 50i. HQ mode (35mb/s).


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Joe Tyler
Re: EX3 and rolling scan lines
on Mar 14, 2009 at 5:50:16 pm

Sometimes (depending on the environment) It can be the frequency of the light vs the frequency of the camera/shutter. It would take a few minutes to test, but try this. Setup your camera to record (any format) and cycle thru the shutter settings 1/60, 1/100 etc. This will eat up light but may solve the problem.

Certain bulbs (usually fluorescent- 50hz) or equipment running at a non standard US voltage (other than 110v/220v) and concert lighting equipment, particularly dimmer boards, are frequently manufactured in the UK and operate through their own power source.

I've encountered this problem quite a few times and everyone blames the CMOS chip, but sometimes it is a simple frequency problem. Of course the chip is the likely suspect.

Good luck


http://www.killianthered.com
DP in the Washington DC Area
EX3 Owner


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Don Greening
Re: EX3 and rolling scan lines
on Mar 14, 2009 at 6:18:47 pm

I also had a look at Mr. Anderson's sample footage several days ago and thought that it looked more like a power frequency issue than anything else. It looked very similar to a computer monitor or television scanning mismatch. It seems to me that people roll out the "rolling shutter" phrase as a catch all to describe different issues.

Standard CMOS technology scans the chip from the top down and over a period of time. CCD chips get scanned all at once. The downside of CMOS then results in:

  • picture skew when motion happens faster than the CMOS chip is scanned
  • half-frame camera flashes

I'm sure that the CMOS chips are more sensitive to power frequency issues than CCDs as well but there are settings in both the EX1 and the EX3 to minimize or neutralize them.

- Don


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Kris Anderson
Re: EX3 and rolling scan lines
on Mar 14, 2009 at 9:39:52 pm

Thanks for the input here guys. The camera in question was a rental so I don't have it at hand to do any tests. The lights in the shot are Martin Mac 2000 profiles. They don't run through a dimmer board but they do have an internal shutter/dimming mechanism.

Info here:

http://www.martin.com/product/product.asp?product=mac2000profileii

The EX3 was a budget call on my part. I originally had 2 HPX3000's booked but had to trim some $$$ for the weekend. It's a bitter pill for sure but I've learned a lot from it.


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