what about the old yellow issue? at DVinfo.net

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Canon GL Series DV Camcorders
Canon GL2, GL1 and PAL versions XM2, XM1.


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Old November 29th, 2002, 01:33 PM   #1
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what about the old yellow issue?

There has been some discussion about bad reproduction of yellows using the GL2 that suddenly stopped. I'm still able to reproduce bad 'yellows' with my XM2, so what about you? Are you ignoring it? Or are you still convinced that XM2 does perfect yellows? What are you doing? Color-correction in post-production?

The XM2 doesn't have problems with all yellows but a specific one. And please don't tell me about Color Phase-Correction it's just nothing more than a workaround.

Or do I have a lemon, too? [sarcasm]
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Old November 29th, 2002, 08:15 PM   #2
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You have a problem with yellows? Really? If I did, I'd contact my dealer for a replacement or for a fix. If it can't be resolved, I'd get my money back.
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Old November 29th, 2002, 08:28 PM   #3
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Frank Granovski, do you own a GL2/XM2?

This issue HAS been discussed but the only thing that resulted so far is that someone just maxed out his color gain to get the yellow he wanted. I wonder how ultra-red his oranges are now...
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Old November 29th, 2002, 10:07 PM   #4
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I do not own a GL2/XM2...but wish for a DVX100, and even more for a DSR570. +_+

Yes, I read that discussion, but you described this yellow problem to be major, since you can still "be able to reproduce bad 'yellows'". You also asked, "Or do I have a lemon, too? [sarcasm]." So I suggested this: if the problem is that bad, (if you have a lemon), then get it fixed, exchange it, or get your money back.
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Old November 30th, 2002, 05:09 AM   #5
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If the white balance is OK (white looks white) try to find somebody who can verify yr cam's Y/C output with a vectorscope. Yellow is a very critical color w.r.t. hue settings (burstphase) and component (U and V) ratios in yr cam.
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Old November 30th, 2002, 02:21 PM   #6
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Tried to post this yesterday but couldn't get back on the site

Mireille

I'm not sure who the "you" is....but I'll bite. I've been working with the gl2 for about as long as anybody, and I'll agree with you that it doesn't do perfect yellows. Nor does it do perfect greens, reds, blues, or anything else...and and as a matter of fact....neither does any other camera on the market...perfect is something that no camera does...not film...not digital. All digital cameras are tuned to certain color ranges by their designers to hit what they feel is the sweet spot....and this may mean that some colors reproduce less accurately than others.

I think the yellow on the gl2 is typically a little desaturated, and a little red. This can be adjusted using color phase ..(I'd call this a tool, not a work around...as it is something that virtually all home TV's have as well as most professional video cameras). You could also use white balancing to shift things the direction you want to go.

On the other side of things...the gl2 produces about the most accurate reds, and some purple tones that I've never seen on my gl1 and xl1s. I guess owners of those camera's should be screaming about this as well. Also...the neutral color balance of the gl2 is one of the best in it's category, as is its overall contrast range...( I think this lower contrast is contributing to the low chroma range of the yellows)...try lowering the setup, shifting the color phase a bit to the green, and increasing the color gain to give you a little more punch in the yellows.

Take a look at this clip...the gl2 is the hand held camera at the left of the stage. Look for the amber highlight in the singers guitar strap...dead on match for the lighting in the club...color phase on the gl2 was set 2 notches to the green...and the camera matched the xl1s and gl1 just fine...except for the deep purple backlights that the other camera didn't even see.

http://homepage.mac.com/barrygoyette/iMovieTheater10.html

Barry
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Old November 30th, 2002, 07:07 PM   #7
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That's interesting _you're correcting the color phase towards green... on my XM2 I have to do the opposite: my yellows got too much green, so I usually correct towards red. But thank you anyways. I've found some kind of compromise between color-phase and post-prod-color-correction (for yellows only). But I'm thinking about replacing my camera because of the other XM2 problem Ken Tanaka was writing about: the 'keyhole'-effect. My camera shows exactly the same vignetting as it has been described at

http://www.dvinfo.net/conf/showthread.php?threadid=3430

So...

Anyways, thanks!
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Old November 30th, 2002, 08:08 PM   #8
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Really? Geez, you must have bought a lemon after all. Sorry to hear that. Personally, I'd be p_ssed but would try to resolve it by exchanging it, or getting a refund. Good luck.
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Old December 3rd, 2002, 03:25 PM   #9
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Mireille, just read Ken Tanaka's tread. The "keyhole" (portholing) is known with most (all) zoom lenses on their extreme zoom-in position specifically at wide open aperture. The effect belongs to the mechanical vignetting and is caused by the large entrance pupil (at that extreme zoom setting), which becomes larger than the focussing lens group diameter, causing the "keyhole" effect and the "F drop". I wonder if you will find a XM2 which at low F number will not show this effect. If you do a check, keep in mind that the human eye rapidly adapts to brightness non uniformity. So you should use fast zoom-in/out in manual low F-number setting on a uniform gray field. Did you know that most TV sets have a 50% brightness fall-off towards the corners... ever noticed?
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Old December 3rd, 2002, 04:40 PM   #10
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Andre, the portholing at extreme zoom-in does show up but that's another story. I get the same portholing with extreme zoom-out and at wide open aperture (in the middle of the zoom-range everything is ok and if I close the aperture some steps it's becoming better). I'm doing this check with Final Cut Pro Waveform Monitor to have a second eye witness. So is this issue known, too? (extreme zoom-out + max aperture + not enough light in the room)
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Old December 4th, 2002, 04:11 AM   #11
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Of course Mireille, brightness fall-off at wide angles (though not the specific issue), is known and normal for all zoom lenses. It relates to the physical lenght of the optics and is known as "natural" or "opical" vignetting.It follows a "cos 4th" power law. Closing the aperture allways results in better uniformity (also in extreme tele mode)
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Old December 4th, 2002, 12:39 PM   #12
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I haven't seen either of these problems on my GL2. As a matter of fact, someone questioned my statement on the dv.com camera forum that I thought the video I shot of a yellow buttercup flower in Ansel Adams Wilderness was as yellow as yellow can be ( and nice green plant stems in the back ground too ). I haven't figured out what all this " hubbub " about yellows is all about. Everything looks pretty realistic to me - which may be a bad thing for some. But I like it.
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Old December 4th, 2002, 12:57 PM   #13
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Craig, would be nice if you could post a still for us.
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Old December 5th, 2002, 12:51 PM   #14
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I'll try and do so soon. Since I edit on a stand alone system, I'll have to use Snappy to do a frame grab. After seeing your frame grabs I think my yellows look better than the ones you posted simply because ( correct me if I'm wrong here ) your parade footage was shot in what looks like overcast conditions and my buttercup was shot in bright summer sunlight at 10,000+' of elevation. Lighting makes a difference no matter what cam one uses I believe.
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