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PostPosted: Wed May 12, 2010 12:38 pm 
Hi everyone !
Is this a "friging purple" or "vertical smear" ?
So bad happen so easy at FZ35. Any way to reduce this problem ?

http://vimeo.com/11673530

Cheers,

Carlos


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PostPosted: Wed May 12, 2010 1:38 pm 
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Arg, Ive forgotten how they call it.
It's due the small sensor of the camera, you only will get this when doing this with bright lamps or the sun.

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Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


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PostPosted: Wed May 12, 2010 2:03 pm 
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As far as i know fringing is on the edges of subjects (only on still images, am i right?)
Like this: http://www.dslrnewb.com/wp-content/uplo ... inging.png
So i would guess this is smear.

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PostPosted: Wed May 12, 2010 6:39 pm 
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It's a video artifact, because the Lumix isnt a pro video camera.

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Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


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PostPosted: Fri May 14, 2010 10:49 am 
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That's too simple ruben ;)

The effect happens on CCD sensors. Simply put, when a cell becomes oversaturated, the whole row can become oversaturated, causing the bright stripe across the image. I think it's called a smear/bleed but I'm not sure.

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PostPosted: Fri May 14, 2010 11:42 am 
This is definitely purple streaking (or smear) in the CCD sensor. It is a sensor artefact due to saturated pixels. By the way, your video is a very good demonstration! When the camera meters the light in the room, the chandelier is over-exposed and saturates the pixels. When the chandelier is metered, the room becomes darker, but the pixels no longer saturate.

Purple fringing is something different. It occurs at the edge of high-contrast areas (e.g. photo of a tree against a bright sky) and is a lens artefact that has to do (to my knowledge) with shorter wavelengths (purple and blue) being refracted more strongly.

OK, back to CCD streaking - how can it be controlled? By
a) avoiding spot sources of light
b) using a neutral density filter when shooting video in bright light (*)
c) possibly setting a slight under-exposure, e.g. -0.3 EV

* A UV filter won't do, because you have to physically decrease the amount of light entering the camera, to prevent sensor saturation.

For my part, currently I don't have a ND filter, so I'll simply try to work with EV compensation when there are bright spots of light. Whatever you do, you must try to clip the light from those spot sources just the right amount so that saturation is prevented.

We've just discussed this subject at Steve's Digital Camera Forums, and dpreview.com also has a thread on it:
http://forums.dpreview.com/forums/read. ... e=33114322

Cheers,
Mark


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PostPosted: Fri May 14, 2010 12:04 pm 
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Citruspers,
Oops, thats right. :oops:
That will make video on a dSLR better, I think;)

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Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


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PostPosted: Fri May 14, 2010 6:49 pm 
Hello Mark ! Thank you very much for explanations.
Interesting, I will do some tests changing EV.

Cheers,
Carlos


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