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EX3 rolling low light noise

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Brett Nelson
EX3 rolling low light noise
on Feb 12, 2009 at 8:19:35 pm

Hello,
I'm a new EX3 user. I'm very happy with the camera so far. I am having an issue in some low light situations. I get a broad faint horizontal band that moves from bottom to top. It's like blurred version of scan lines on a computer monitor (except on the whole screen not on a computer monitor in the shot). Has anyone run into this?

Thanks!

Brett


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Craig Seeman
Re: EX3 rolling low light noise
on Feb 12, 2009 at 8:22:19 pm

Low light is not no light. What's the light source? Fluorescents near by?



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Brett Nelson
Re: EX3 rolling low light noise
on Feb 12, 2009 at 8:37:32 pm

Yes, sorry for the sketchy details. I've noticed it more fluorescents, but I also noticed it shooting a shot outside at night, which has an artificial light source on the building.

Thanks!

Brett



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Noah Kadner
Re: EX3 rolling low light noise
on Feb 12, 2009 at 10:18:48 pm

Google for 'rolling shutter.' Welcome to the world of CMOS.

Noah

Check out My My FCP Blog and my new RED Blog. Unlock the secrets of the DVX100, HVX200 and Apple Color.
Now featuring the Sony EX1 Guidebook,
DVD Studio Pro and How to Light Interviews.
http://www.callboxlive.com


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Brett Nelson
Re: EX3 rolling low light noise
on Feb 13, 2009 at 4:39:38 am

Noah,
I thought the CMOS rolling shutter was when flashes go off. I did a lot of research (I guess not enough) about potential problems with the EX, I did not know that fluorescent lights would also be a problem. This is a steady rolling from bottom to top.

So what's the best solution in a situation like this?

Thanks!

Brett



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olof ekbergh
Re: EX3 rolling low light noise
on Feb 13, 2009 at 1:24:28 pm

Try different shutter speeds.

I have found that some christmas lights that are white show up as red blue green and white. I think those were LED lights. It looked good but was not what I was shooting, the client pointed it out to me as we were reviewing the footage in the editing suite. The lights are very small in the shots, 9 pixels or so.

I guess this is just a rolling shutter thing.

Remember the vertical line from some CCD's on beta cams when a bright was in the shot.

Olof Ekbergh


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John Cummings
Re: EX3 rolling low light noise
on Feb 13, 2009 at 2:57:10 pm

I ran into the same situation last week with the EX3. Running and gunning in a department store, shooting 30p, I noticed the rolling band.

Wouldn't changing the shutter in 30p actually change the shutter angle? Would this have minimized the problem, or is this just a cmos issue one has to live with...?



J Cummings
Cameralogic/Chicago
cameralogic.tv
HDX-900/HDW-730S/DXC-D50


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Don Greening
Re: EX3 rolling low light noise
on Feb 13, 2009 at 7:56:33 pm

Both the EX1 and EX3 cameras have an ECS (extended clear scan) shutter mode to deal with lighting frequency issues, especially with fluorescent fixtures. This is also the same adjustment used when shooting a TV or computer monitor to avoid scan frequency mismatches. For setting the EX1 ECS shutter go to page 43 of your owners manual. I don't have an EX3 manual so you're on your own there.

- Don


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John Cummings
Re: EX3 rolling low light noise
on Feb 14, 2009 at 2:49:27 am

Well, Brett didn't mention what frame rate he was shooting in, so I don't know if it's the same issue. I've dealt with shutter issues shooting under fluorescents that usually show up as shifting colors, but this seemed like an entirely different issue with the rolling band...so is it a cmos artifact or simply a shutter fix?
It's also weird that it happens under street lights...

Ok, it's mentioned in the appendix...page 141.

J Cummings
Cameralogic/Chicago
cameralogic.tv
HDX-900/HDW-730S/DXC-D50


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Don Greening
Re: EX3 rolling low light noise
on Feb 14, 2009 at 6:33:19 am

[John Cummings] "so is it a cmos artifact or simply a shutter fix?"

Since CMOS chips get scanned from top to bottom as opposed to CCD's that get scanned all at once I would suspect that CMOS technology is partially to blame and instances of electrical frequency mismatches will be more obvious in the viewfinder. I just fired up my EX1 under fluorescent lighting and couldn't get it to do the rolling. I'm in NTSC land with 60Hz power. My camera was in 30p mode with a fixed shutter of 1/60th sec. The picture was rock solid. If you set your ECS to automatic more than likely you'll have the problem for a few seconds when you first start up the camera and then it goes away. That's been my experience with ECS set to auto.

There are some folks (including myself) that have experienced the rolling frequency thing in broad daylight when the camera is first turned on but it goes away in less than 10 sec. Not that I've tried it but I've heard from reliable sources that the EX optical image stabilization is also partially to blame for the funky picture (if it happens at all) in daylight shooting. Maybe turning OIS off will help the fluorescent issue as well.

- Don



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Kevin Jones
Re: EX3 rolling low light noise
on Feb 14, 2009 at 4:45:28 pm

In the past with a different camera, while shooting around large manufacturing machines with intense magnetic fields, I have seen a rolling like you describe in my viewfinder.
Was happy to see later that the rolling had not been actually recorded.
Only appeared in the viewfinder.


kj



2.5GHz Quad-core PowerPC G5
Final Cut Studio 2


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Brett Nelson
Re: EX3 rolling low light noise
on Feb 14, 2009 at 8:56:08 pm

Thank you all for the feedback. This is a big help. I'll have to check on Monday, but I think my ECS was not set to auto. I was shooting 24p @ 1/48th.

Kevin, you mentioned a funky viewfinder image around big machines... I shot on top of the Sears Tower once with an XL1. After being on the roof for about 5-10 minutes, the viewfinder image went completely to grass. I thought the camera died and wondered if I would get any useable footage. The footage was fine and the camera never had that problem again. I guess 100s of 1000s of watts of power transmitting a couple hundred yards away wasn't ideal.

Brett



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Robert Marty
Re: EX3 rolling low light noise
on Dec 8, 2009 at 8:20:35 pm

I had the same problem when I took mine out of the box.
I soon found out that it had nothing to do with the cmos.
Sony directed me to make a change on my power settings.
Some cameras come preset for power in Europe not North America.
This setting was able to fix my problem.
Have a look at your menu and make the appropriate changes.
This also reduces strobing if you have an issue with that as well.

Cheers,

Rob


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