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Ghosting artefacts using HPX 500


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#1 Emil Soderman

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Posted 28 January 2009 - 03:59 AM

Hello

I was wondering if someone here could help me identify an artefact problem I got using a Panasonic HPX 500 some time ago. In the picture attached you can see what I’m talking about, it’s the blue “ghosting” around the edges of objects, mostly in high contrast clearly, but if you zoom in on the pic you can see its really everywhere. It’s even on the guy with the snowboard and on the boards beneath him where the contrast really isn’t that high. Anyone got an idea what the problem is called and what causes it? The lamp in the background is a 1200 HMI lighting the Smoke.

I’ve managed to repair it quite well using the channel mixer in AE to remove two of the RGB channels on the problem area, and then correcting back the original colour to match the rest of the picture. Would be interesting to get a real explanation to why it occurs though.


Thanks allot!

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#2 Dickson Sorensen

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Posted 11 February 2009 - 11:05 AM

Not sure, but the first question is what kind of lens are you using? The HPX 500 has CAC (Chromatic Aberration Compensation) for certain lenses. What I see in the picture you attached looks like chromatic abberation. If you are using a CAC lens make sure the feature is on. It can be caused by less than perfect optical performance of your lens, a filter or adapter on the lens, or perhaps misalignment of one of the chips (though I doubt the third possible explanation). Can you reproduce it under other circumstances?
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#3 Satsuki Murashige

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Posted 11 February 2009 - 11:41 AM

I agree with Dickson, that looks like chromatic aberration which is probably an artifact of the lens you were using.

Also, the HPX500's lens shading menus are not as sophisticated as an F900 or Varicam type camera, so any additional in-camera compensating that was done to get a neutral response from the lens might not be adequate.
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