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October 13th, 2004, 12:52 AM | #16 |
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Yes. I noticed the red channel "jaggies" too. But I think it is a DV compression issue, since I shot a test with a DVX100A 6 months ago, and there was this one guy with extremely red shirt. There was exactly the same kind of jagginess with those shots too.
So I think it's not a XL2 issue, but an annoying DV compression artifacts. I don't remember if the jagginess was there in my interlaced material... |
October 13th, 2004, 06:19 AM | #17 |
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The extra noise in the footage posted by A. J. deLange could be the fact that a 1/30th shutter speed was used for 30P instead of 1/60th, as 1/30th increases the sensitivity to light and therefore would probably introduce some noise/grain.
When I started playing around with the 24P mode on my new XL2 I noticed the default shutter speed was always set to 1/24th - so now I always change it to 1/48th for a better image. Can anyone explain why Canon would default their camera settings this way? I can't figure it out... |
October 13th, 2004, 09:38 AM | #18 |
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The red jaggies on the DVX are pretty well documented on adam wilts site. So far I haven't seen much of them on my xl2, and while they occasionally are visible on the computer screen...I have never seen them appear when viewed on my HD set or SD monitors/tvs that I'm using.
Until I saw A.J.'s stuff I was under the impression that they would be less of an issue with the xl2...now I'm not so sure. Barry |
October 13th, 2004, 07:03 PM | #19 |
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I think the jaggies on the pinwheels are indeed compression artifacts. They seem to be present in the other colors as well but certainly are most noticeable in the reds. I don't know if this is the reason or not but those reds colors are saturated enough that the chroma magnitude is greater than 100 (as seen on the FCP vector scope).
As for the noise I think the explanation is that it was dark enough that a gain up of 12 dB was required to get reasonable brightness on tape. This raises the noise floor 12 dB relative to 0 dB gain (which setting I always hold fixed) - enough to make it quite noticeable especially in those parts of the clip where most of the histogram is below 50 IRE. All the shutter speeds were 1/30. I'm not sure I understand how a faster shutter speed would improve the situation. To me 30p means that the whole CCD is read 30 times a second (and that separation into 2 sub frames is then done for DV 60i encoding on to tape). During the exposure time the noise level is integrated as is the signal. As integration time increases the signal to noise ratio increases as the square root of the integration factor. Thus doubling exposure (integration time) would improve SNR by 1.5 dB. What am I missing? A.J. |
October 13th, 2004, 08:20 PM | #20 |
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By the way, thanks AJ for posting the footage. What are your impressions of the camera?
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October 13th, 2004, 10:26 PM | #21 |
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Maybe the shutter speed does not contribute to the fact the images look noisy, but from the playing around I've done with our XL2 I have only seen that amount of noise when shooting well over +3dB. I usually shoot in the Manual setting and keep my gain between -3dB and 0dB.
As for Mark's original post "Where's the XL2 footage", I just uploaded some on this thread: http://www.dvinfo.net/conf/showthrea...threadid=33417 |
October 14th, 2004, 01:27 PM | #22 |
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Filming stars with Xl2
I pushed the Xl2 to its limits and checked whether one is able to film stars with the camcorder. Suddenly, for my surprise, I recognized the Dipper in the viewfinder. The footage can be downloaded from
http://www.luontovideo.net/XL2-lens-test.html Be aware, couple of the stars of the Dipper were behind the trees, and that's why they are not visible or they are blinking. Settings: Shutter 1/6s, gain +18db, black=stretch, NR=high |
October 14th, 2004, 02:24 PM | #23 |
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Lauri
I was out of the house early one morning last week...still dark...I had the camera on progressive at 12db probably 1/30 sec...I was not trying to see stars, but I was surprised to see several show up on the footage, brighter ones for sure...but still a nice surprise. Barry |
October 16th, 2004, 09:33 AM | #24 |
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Impressions
What are my impressions of the XL2? Definitely not a quantum leap wrt the XL1s but definitely a better camera. At first I couldn't handle the darn thing. It isn't a great design ergonomically and while the shoulder pad may actually ride over your shoulder there is no weight on it because the lens is so heavy. It's probably worth trying the dual battery thing just to see if getting some weight back there will allow it to ride on the shoulder. I find myself supporting it by the wrist strap and the protrusion which mounts the iris control. Since I always shoot manual my hand has to be there anyway but at first I found this very clumsy. Like a new rifle, a new camera feels clumsy and not as good as the old one in so many ways and I didn't think the results were that much better than the XL1s to the point that I considered returning it. So I took it to Mexico for a week where it was my constant companion (anything you value should be your constant companion in Mexico) and found that just like the new rifle, once you have carried it for a while it becomes a part of you.
What I do like about it very much is the 16:9 aspect ratio. I just like that aspect ratio and that is why I bought the camera - that and the true 30p. The video definitely looks good on a computer screen and on a TV set but I haven't done any resolution chart tests to see if the pictures are really sharper than the XL1s or not. What I don't like is the ergonomics and I'm not sure the SNR is that great even in relatively bright light. I'm also not sure the AIS is up to snuff. I cannot hold it at 20X unless I adjust my footing and it is dead calm. I almost suspect that the servo loop bw is too high on the particular S/N I have and wonder if anyone else has experienced similar problems. I know part of it was a learning curve issue because I'm better with it now than out of the box but I'm still not good at long focal lengths. Bottom line: I wouldn't hesitate to recommend it highly to anyone who needs or wants to change lenses (the ability to put my old Nikkors on it is another big plus for me) but I don't think that all XL1s owners need to sell their XL1s's and buy an XL2. I'm not a pro and I have no experience with the DV100X so I can't compare to it (or any other high end gear). One more tidbit: While in Mexico I visted the Arbol de Tule. This is the world's largest tree - 45m in circumferance. I was told that I could not take the XL2 inside the fence which surrounds the tree (this is the basis of the town's economy - there is a permanent police presence there) because large video cameras produce emanations which harm the tree. Small ones do not. Prospective buyers may want to consider this. A.J. |
October 16th, 2004, 10:14 PM | #25 |
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A.J.,
Thanks for the footage. I am downloading it right now. All the other footage on the net has been compressed to MPEG4 or MPEG2. I have been waiting for some native DV footage and that is what yours appears to be. Looking forward to using 16:9 in FCP for the first time. Greg |
October 17th, 2004, 11:39 AM | #26 |
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Going back to the red fringing, I have been a DVX owner for about a year, and this is something that tends to pop up every now and then. At first it was a problem, as I found no way to get rid of it, but then I discovered a cool little effect in vegas that gets rid of it. I think it is available also for FCP and Avid, but I'm not sure about Premiere. You can see some of the results here.
http://www.stefweb.net/chromatest.jpg This footage was taken in the worst of conditions, really red lighting and not a lot of it, about equal to my living room. I shot with 6db gain and 1/24 shutter speed in 24p, iris wide open. This is definatly something that is fixable, and while it is true that it doesn't always show up on an interlaced television, if your ever transfering to film, or showing on a progressive scan television, it is much more obvious. Hope this helps. |
October 17th, 2004, 12:02 PM | #27 |
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stefan...
Nice trick...thanks for turning us on to it. barry |
October 17th, 2004, 12:29 PM | #28 |
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Oh, by the way, the filter is called "chroma blur" in vegas, but it might be called something else in other NLE's
Also, make sure that you look at the jpg at 100%, I noticed that some web browsers tend to scale the image to fit the screen, but it seems to get rid of the good looking effect. |
October 18th, 2004, 08:44 AM | #29 |
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I guess I'd like to know if there is an equivalent "chroma blur" tool for Adobe After Effects or Premiere. I'd hat to have to buy vegas just to correct this issue when it arises.
Thanks, |
October 20th, 2004, 02:41 AM | #30 |
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The "red" problem is a known issue with a lot of camera's out there,
I first noticed it on my XL1S. I agree it is a compression issue since the chroma blur fixes it basically. I've never seen it on a TV set with my DV footage (probably due to the way a TV works and has a lower resolution) and also transcoding to MPEG2 for DVD fixed this issue for me as well.
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