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Old May 7th, 2009, 12:13 AM   #1
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CA caused by pixel shifting?

So I just got back from a big shoot at the Orlando convention center. I was hired for 4 days to film a conference 11 hours a day. I had the JVC 700 with a Kessler crane setup. The director loved the camera Thank God , So anyway its seems to me either there is something wrong with the processing of the camera or the fujinon has very bad Ca . Here is the weird thing to me , I was watch my live shots HD SDI output . It looked amazing no Ca or not that I could see. Upon play back here in my house back home I see Ca mostly on Closeups. I didn't see it live. So is it possible that the new JVC pixel shifted technology is faulty ? I mean the shoots look gorgeous thanks to good lighting but I see lots of weird fringing that doesn't look like Ca. I would upload clips but I will do that another day .

Thanks for listening to my rambling

Doug T
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Old May 8th, 2009, 02:13 PM   #2
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Hey Doug - how about a more contextual title? Just keeps archival threads a bit neater. :)

Personally the speculation that fringing is due to pixel shifting upscaling I find very dubious. Certainly, this is not indicated by your comparison of live monitoring to playback.
Logically, the difference would only be the compression or difference in your monitoring, no? The live HD-SDI monitoring would be post the pixel-shifting stage.

Is it possible that some of the fringing might be due to ambient convention lights? How about the monitoring systems you are seeing this with possibly exacerbating the problem? I do see CA/fringing on high contrast edges, especially with overly bright areas when exposing for a darker foreground element. It just hasn't been common that it can't be avoided or at least minimized. Have you directly compared it to other HD cams in the same situation?
I think what we see is part of the territory for HD 1/3" ccds with wide range lenses. Telephoto range of lens, overexposed areas, extreme f-stops are all triggers to be watched when combined. Better glass will help - especially for wildlife shooters who face challenging field conditions.

Post-processing can help a lot. I'd be interested in what people are finding the best approach for mitigating fringing. Tweaking "channel offset" in the blue channel is one way I've improved some shots, and I think there are plugins that can automate a more sophisticated approach.
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JVC GY-HM-700 with 17x5 lens, MacPro 3.2ghz 8-core, 18gb. (JVC HD200 4 sale soon)
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Old May 8th, 2009, 03:15 PM   #3
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sorry about that post Sean lol

Well its happening indoors or outdoors so i think it is the lens and some compression and yes with the plugin filters I have for FCP I am able to remove 98 % of the problem



Doug
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Old May 8th, 2009, 05:45 PM   #4
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what FCP plug in is that?
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Old May 8th, 2009, 07:38 PM   #5
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tiffen filters V2

Tiffen filter package for Fcp . Its an amazing package

Dfx V2 Home Page - Tiffen.Com

Chromatic Aberration Filter
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Old May 9th, 2009, 12:24 PM   #6
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I'm back and I've changed the title of this thread to reflect the question.

My short answer is "no," pixel shifting doesn't cause chromatic aberration.

It's all about the lens and the prisms. I know this because it is possible to create images in 1080 mode without any CA whatsoever.

I've uploaded a new video of some stuff I shot last weekend with the Fujinon 17x5.
HM700 + Fujinon 17x5 Lens on Vimeo The original file is available there for download and should play in VLC, WD media player or PS3. If not, change the extension for .mpg to .m2t

As soon as a I have a chance I will put together a detailed lens comparison of the Canon 14x4.5 vs Fujinon 17x5. As I've said before I think the Fujinon is actually the better deal if you get it bundled with the HM700. It retails for $3500 on its own!
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Old May 10th, 2009, 07:57 PM   #7
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Tim - sorry - but that is some of the softest imagery I have seen in awhile. I would be having a coronary if I spent the $$$ to get the JVC 700 and Fujinon and that was as sharp as it got.

Is this a Vimeo issue?
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Old May 10th, 2009, 08:24 PM   #8
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If you go to the Vimeo page and scroll down looking at the right-hand column of information, near the bottom should be a link to download the original uploaded file. Then you can watch it without the re-encoded Flash files that Vimeo plays in its main viewer.
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Old May 10th, 2009, 08:40 PM   #9
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Bob - I have seen some fairly sharp Vimeo clips - many are soft - I'll download and view going forward - Vimeo is too much of a variable to know what is what. Thanks.
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Old May 14th, 2009, 06:12 AM   #10
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Same problem I am having and reporting on this forum for some weeks. But I got in bundle the 16x (old ones of the GY-200) not the 17x. I also for a momento supposed it was due to pixel shifting. Tim says "no" and probably he is right but maybe truth is halfway through. I mean .. with pixel shifting the CCD dedicated to a specific colour might enhance CA because all light info on that "position in space" comes to only one CCD and if lenses are sending a little CA pixel shifting might make it worse. But this is just an idea.. and we should wait proper tests that Tim promised with 17x and 14x Canon. Maybe TIM.. can you add tests with the 16x Fujinon.. just because JVC Italy bundled these lens. Thanks
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Old May 14th, 2009, 06:17 AM   #11
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Quote:
Originally Posted by Doug Tessler View Post
Tiffen filter package for Fcp . Its an amazing package

Dfx V2 Home Page - Tiffen.Com

Chromatic Aberration Filter
HI Doug.. these filters seem quite interesting... 100$ for all that? But it says Photoshop not Final Cut? Can I use them on video? Do they render fast?
M
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Old May 14th, 2009, 08:34 AM   #12
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no its for Final cut Pro

Look for the one for FCP thats the one I have

Doug
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Old May 17th, 2009, 08:41 PM   #13
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the final cut version is 599.00. How is the CA filter? does it work well? and, I'm thinking the filter will degrade the image quality a bit for everytime it is rendered. but is it noticeable?
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Old May 17th, 2009, 09:28 PM   #14
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hi

the filter is great and i see no degrading of the rendered clip.You need to experiment for the best results but the filters are great

Doug
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Old May 18th, 2009, 11:47 AM   #15
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re

Quote:
Originally Posted by Doug Tessler View Post
the filter is great and i see no degrading of the rendered clip.You need to experiment for the best results but the filters are great

Doug
I am an user Xh-A1 and I must say - you are a God .-) ! Thanks for this plugin, it works perfectly with Avid MC3.0 .
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