vertical magenta lines - chromatic aberration? - Page 2 at DVinfo.net

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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old December 13th, 2006, 09:48 AM   #16
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The problem seems to happen with all cameras in this price range. For a direct comparison between the A1 and the FX7, please check Wolfgang's HDV blog on http://www.fxsupport.de/14.html and download the following pictures:

http://www.fxsupport.de/pic/06/12/09/fx7_02.jpg
and
http://www.fxsupport.de/pic/06/12/09/a1_01.jpg

look at the bottom "V" of the tree. Don't you see similar green/purple fringing on both cameras?

Now look at
http://www.fxsupport.de/pic/06/12/09/fx7_01.jpg
and
http://www.fxsupport.de/pic/06/12/09/a1_02.jpg
and check the trees on the left hand side of the picture. Don't you see similar green/purple fringing on both cameras again?

As far as I know, the chromatic aberration is almost unavoidable with zooms, and is noticeable on still cameras as well. One way to minimize it is to close the iris or to zoom in a bit, but this may not always be possible of course.


Übrigens: vielen Dank an Wolfgang Winne für seine sehr informative Web-Seiten!
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Old December 13th, 2006, 10:50 AM   #17
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Jerome, this site is a real treasure chest! Good example of German thoroughness :)
Danke an Wolfgang Winne auch von mir!
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Old December 13th, 2006, 11:14 AM   #18
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The fringing seems slightly more obvious on the A1 in that it doesn't fall off so softly... It's like a solid magenta outline rather than a gradient.

However, it's definately there on both cameras - using different types of sensor. And CMOS aren't supposed to bloom, so it may not be a sensor problem after all?

Whatever's going on, I never saw this sort of fringing with the FX1/Z1 in a way that made me draw breath through my teeth (although I accept that these cameras do display fringing too).
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Old December 13th, 2006, 04:49 PM   #19
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comparison

If i understand the site correctly, it looks like the pictures listed above are

1. Still snaphots from memory stick, not video capture
2. the A1 photo was resized using photoshop

the resizing may explain why the A1 halo looks different?

Anyone have a source for V1(release quality) vs A1 video comaprison?
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Old December 13th, 2006, 05:10 PM   #20
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the canon is overexposed. not a fair comparison.
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Old December 13th, 2006, 06:32 PM   #21
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I'd say not only is the Canon over exposed, but the sharpness appears set substantially higher than the Sony's. Neither of those attributes are likely to reduce fringing issues...
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Old December 13th, 2006, 06:50 PM   #22
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Not a comparison to the A1, But Douglass Spotted Eagle has a still and some clips of the Sony at:

http://www.sundancemediagroup.com/ar..._camcorder.htm

You can see some fringing in those. Note the purple cords on the parachute (among the white ones) in the still or video. It's minor, but it is still there.
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Old December 13th, 2006, 07:41 PM   #23
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I'm really beginning to believe that these four thousand dollar camcorders simply don't offer the optical and compression quality of seventy thousand dollar camcorders with forty thousand dollar lenses.
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Old December 13th, 2006, 09:09 PM   #24
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The pictures shown above (Wolfgang blog) from the A1 are 'straight out the box' he did nothing to get the best picture. That is what he is telling on his blog.
If you buy the 70.000 cam you need to work on the picture too, so I say ' I want it all done at the highest quality in the automatic mode'.
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Old December 14th, 2006, 12:24 AM   #25
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Wolfgang's pictures are from the memory card, not the tape but were not otherwise tweaked. Still: I did not post them for people to compare which of the two cameras has the worst CA (you can't really use them for that), but to show that two modern, competing cameras in the same price range exhibit CA.

If you want to compare the two cameras, you would need pictures from tape and a set of pictures at various zoom length and iris settings, exposed and sharpened in the same manner.
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Old December 14th, 2006, 09:04 AM   #26
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For anyone who's having problems, River Rock Studios have a $9.99 plugin for FCP that can (apparently) fix CA.

http://www.riverrockstudios.com/rive...cheapLens.html

It's actually designed to simulate CA, but the sliders also go into negative values :).
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Old December 14th, 2006, 09:09 AM   #27
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That's interesting! Is there a similar plugin for Vegas?
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Old December 14th, 2006, 09:35 AM   #28
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Sorry, I don't know of any that do the same for Vegas.

The slightly ($485) more expensive 55mm plugin (which includes a CA fix) from Digital Film Tools supports FCP, Adobe AE and Avid.

But I haven't come across anything for Vegas...
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Old December 14th, 2006, 10:09 AM   #29
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Quote:
Originally Posted by Alex Leith
For anyone who's having problems, River Rock Studios have a $9.99 plugin for FCP that can (apparently) fix CA.

http://www.riverrockstudios.com/rive...cheapLens.html

It's actually designed to simulate CA, but the sliders also go into negative values :).


In theory, it should work but I don't think that this plug-in will be usable to minimize CA in real life. Similar plugins are integrated in the raw converters of SLRs. From personal experience I can tell than using them is very tedious. Using them for video will be excrutiatingly tedious, because CA has to be adjusted for each focal length. So each time you zoom in and out, you will have to continuously readjust everything.

Now, if one had a plugin which did that automatically (they exist for SLRs from dxo labs), I'd be telling another story.
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Old December 14th, 2006, 10:21 AM   #30
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Once again... fringing has many causes. Please stop calling it CA; that's misleading.
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