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CMOS and rolling shutter - solution?

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Ryan Mast
CMOS and rolling shutter - solution?
on Feb 6, 2008 at 4:31:49 am

I'm saving up for my own camera. I want HD, and I tend to like Sony cameras because I'm comfortable with them, and I like how they handle. But beyond choosing brands or tape v. tapeless... I'm concerned about CMOS cameras.

I've been using a Sony A1 for over a year, and I like its picture quality and practicality, especially for the price range. But the rolling shutter issues with the CMOS seriously bug me. It's not noticeable all in low-action scenes, like interviews or landscapes, but any motion, or camera shake, or whip-pans look wavy. Applying SmoothCam fixes overall camera shake, but it distractingly accentuates the rolling waves. Four-point motion tracking and match-moving in Motion also becomes more difficult, because a tracked plane doesn't have the waves like the rest of the picture.

Does this bother anyone else, or does it just bother me because I can recognize it now? Does it bother normal viewers? Should I get over it? Anyone know good workarounds?

And the next question is... are there any camera manufacturers that have developed a workaround for the rolling shutter issue with CMOS sensors? I like the form factor of the EX-1, but the rolling shutter issue honestly is a deal-breaker for me, because it limits how much motion I can reasonably allow in a shot. I'm not shaking or waving the camera all the time, but I do like being able to use quick motion when it's appropriate.

What do you all think? Especially those of you that use CMOS cameras in professional settings -- do they work for you? Is it acceptable for broadcast?



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Dan Brockett
Re: CMOS and rolling shutter - solution?
on Feb 6, 2008 at 8:59:23 pm

I think your concerns are very valid. I really like the EX-1 but this issue also is a deal breaker for me. Keep in mind that even the RED camera has this issue and unfortunately, it seems as if all of the manufacturers are leaning toward CMOS technology with a rolling shutter.

If you are around flashes, flashing lights or a lot of motion, rolling shutter artifacts can really nail you. While I like many of the features on the EX-1, I am sticking with the HVX-200 for the time being. We'll see what Panasonic has up their sleeve to fight against the EX-1, we are getting more and more due for an HVX-200A or an HVX-300 or something new that I am sure will be amazing.

Best,

Dan

Providing value added material to all of your favorite DVDs


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Eric June
Re: CMOS and rolling shutter - solution?
on Feb 11, 2008 at 5:28:41 pm

Ryan and Dan obviously understand what the CMOS sensor rolling shutter issues are, but for anyone reading this thread who isn't familiar with them, this is a great explanatory article:

http://dvxuser.com/jason/CMOS-CCD/


My ATV, Skiing and Hang Gliding videos: http://GrizzlyGuy.TV


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Eric Mousel
Re: CMOS and rolling shutter - solution?
on Feb 11, 2008 at 8:54:05 pm

Ryan,

I, very much like you, am saving up to buy an HD camera and also like you am looking at Sony. The EX-1 definitely impressed me at first, and still does in many respects, but the rolling shutter issues and 4:2:0 color space are near-deal breakers for me. I plan to use my new camera (whenever I get it) for compositing, fast motion "run and gun" footage, studio recording and a plethora of other things. To be honest, if I had the money to buy today I cannot truthfully say whether I'd go for an HVX200 or an EX-1. Both have their ups and downs and, like Dan said, I'm looking forward to Panasonic's answer to the EX-1. Even so, whatever that new Panny offering is, you can be sure it won't solve all my/our problems. Some amount of compromise will have to be made on our parts (unless we win the lottery that is...) I look forward to hearing what your eventual choice will be when you're ready to make it.

Eric Mousel
Creative Services Producer
ABC17/FOX38/MyZOU32/ABC StrmTrk 24/7


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Justin Vaillancourt
Re: CMOS and rolling shutter - solution?
on Feb 13, 2008 at 4:45:20 pm

I've also read the EX-1 takes a serious resolution hit during fast motion. Not artifacts, just a resolution drop.



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B.J. Ahlen
Re: CMOS and rolling shutter - solution?
on Feb 13, 2008 at 6:38:02 pm

In the comparison between the HVX200 and the EX1, you can't say that the "4:2:2" of the HVX200 is better than the "4:2:0" of the EX1.

You were concerned about chromakey, so let's look at the absolute chroma resolution of the two cameras.

The HVX200 has a luma resolution of 960x540. 4:2:2 color sampling gives it a chroma resolution of 480x540.

The EX1 has a luma resolution of 1920x1080 (full raster sensor). 4:2:0 color sampling gives it a chroma resolution of 960x540, i.e. twice the chroma resolution of the HVX200.

In practice, both cameras do chroma interpolation (and the HVX200 does a pretty amazing job of quadrupling its recorded CCD resolution to get to 1920x1080 also).

For chromakey work, you can also use the HD-SDI spigot on the back of the EX1. This has full SMPTE 10-bit 4:2:2 1920x1080 with no padded bits, interpolation or anything else.




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Ryan Mast
Re: CMOS and rolling shutter - solution?
on Feb 16, 2008 at 5:20:44 am

Okay, well here's where I start to get confused...

The A1 has the rolling shutter issue, been there, experienced it.

But now it seems that this article is saying that Sony has solved the rolling shutter issue in the EX-1 with a special system that "enables lightning-fast parallel read-out of columns (virtually eliminates rolling shutter effect). It's the same technology featured in the EX1 and Sony's new Alpha digital SLR line..."

Can anyone speak authoritatively on this? EX-1 owners? What's your experience been?



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