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Canon XL and GL Series DV Camcorders
Canon XL2 / XL1S / XL1 and GL2 / XM2 / GL1 / XM1.


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Old August 13th, 2004, 07:18 PM   #31
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Clive

Moire....

I'll go back to the post I made earlier regarding the moire. This is common, expected, normal and has been around since the earliest days of TV. Remember the old adage about not wearing a tweed jacket to an interview...you'll look like you've got ants crawling all over you...this was, and is moire, and it is cause whenever any input pattern approaches the the same frequency of the capturing matrix, as well as the output device matrix...Watch a little low end reality television and you'll see it all over the place...

the effect is heightened by increases in sharpness at the capture end and can be lessened by turning down camera sharpness, filtering the lens (or chip), or by changing the frequency of the offending pattern (by moving closer or further away from the subject).

Barry
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Old August 13th, 2004, 09:30 PM   #32
 
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Crying wolf? when will it ever stop? As Barry said, this is pretty commonplace in (raster)scanned images. BFO( beat frequency oscillations) are commonplace. There are simple fixes. not the least of which are changing zoom ratio, slightly. Even if it can't be fixed during the shot, it can readiy be dealt with in post, anti-moire filters. So, what's the big bruhaha? These images are astonishing for their quality. I'm already sold on an XL2.
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Old August 13th, 2004, 10:05 PM   #33
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I recall the first time a moire pattern really jumped out at me as kid and really held my attention. It was some fairly famous news video shot in the basement of the Dallas courthouse just after the Kennedy assassination and IIRC before Ruby was shot. Some reporter or court official is talking to the camera, and he wore these heavy metal frame glasses which produced the most bizarre reflective stroby pattern with every slight movement of his head, in my youth to me they looked like some kind of wierd X-ray specs. What's that? I thought, totally lost (still lost) in the hypnosis of that very bright pattern, which made me ignore the entire context of that moment. If I saw it again today it probably wouldn't be a big deal, but back then it really pulled me out of the moment.
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Old August 13th, 2004, 11:44 PM   #34
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Yeah I see Moire on commercial Movie DVD's. Moire doesn't bother me as I almost expect it in video. The other artifacting I saw was what made me sit up and take notice. The images were FULL of this artifacting.

Thanks Barry for trying out a stuff from your DVX etc.

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Old August 14th, 2004, 03:34 AM   #35
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So everyone thinks that moire is acceptable and is commonplace or that it can be fixed by antialiasing filters. Mmmm.

1. If shooting a film, will you or your DOP be happy about always being compromised on zooming just because of moire?

2. Do you feel happy that to eliminate this level of moire would result in filtration effects which will soften the image to quality comparable to the DVX100 potentially worse? If so, what is the point of having a camera capable of such sharp imagery if its unusable?

3. Since the effect is dependant on what you're shooting, do you think its acceptable to have full res sharp images in your film intercut with certain shots which are softer to get rid of moire through post filtration? I don't think so.

I sense a complete contradiction with this camera. This camera is aimed at film makers. Progressive scan, interchangeable lens, yet its held back by video technology which has been around for years and yet somehow, JVC seem to have bypassed it with the HD10?? What surprises me is that judging by the posts here, its being forgiven for not fully delivering what its promising already.
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Old August 14th, 2004, 03:52 AM   #36
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"The image of the gull looks much clearer than the images on the simplyDV site. In fact the long shot of the building towards the bottom of the review looks simply awful to me having used the camera. I think the image quality is superb with the exeption of this patterning."

I have to disagree Clive. Whilst the gull looks superb - quite as good as anything I've ever seen from DV - the moire shot of the buildings has some serious artifacts that cannot be accounted for by the moire patterns alone.

I have imported the stills into Xpress Pro with Mojo and I watched them on a 700 line broadcast monitor with component in. In comparing the building shot to the gull and those from the Simply DV article, there is something very wrong. The windows and the sign have terrible resolution. The moire on the bricks I agree with others is not altogether an unusual phenomenon in all DV cameras - but the line break up in the lamp and sign seem to be interference of some kind other than moire.

I realise that you were probably hand held for this shot - but the resolution is so far away from the gull shot that I feel there must have been something else going on to have such a poor result.

Best regards,
John.
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Old August 14th, 2004, 05:26 AM   #37
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Clive: I would like to know if you can record an analog signal
through the XL2 over firewire to your computer without first
going to tape (as with the XL1S). Since the GL2 has this feature.
Would be great if you could add that test to your review.

Also, I'm seeing a dotted line on the top of your images. I'm
assuming this is coming from the camera as well? Can't remember
seeing it in any other images I've seen.
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Old August 14th, 2004, 10:55 AM   #38
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<<<<<1. If shooting a film, will you or your DOP be happy about always being compromised on zooming just because of moire?

clive- if I was shooting film...I wouldn't have this problem..If I was shooting video...any camera will produce this effect given the conditions I described earlier

>>>>>>2. Do you feel happy that to eliminate this level of moire would result in filtration effects which will soften the image to quality comparable to the DVX100 potentially worse? If so, what is the point of having a camera capable of such sharp imagery if its unusable?

Unusable?...all digital cameras produce moire of one type or another give the criteria I mentioned above...does this make these cameras unusable? You have shown us three photos, one of which shows moire only on your monitor--the moire doesn't exist in the actual image--does this make the xl2's sharpness unusable..what about the seagull, the carousel? My hasselblad/Imacon ixpress 132C 22 megapixal produces some of the most amazing moire I've ever seen (when I shoot a moire chart!), and I do have to be careful with certain fabrics...but does that make it unusable on my commercial advertising, portraiture, fashion, architecture projects etc? (my clients apparently don't think so...nor do I)

>>>>>>3. Since the effect is dependant on what you're shooting, do you think its acceptable to have full res sharp images in your film intercut with certain shots which are softer to get rid of moire through post filtration? I don't think so.

Again...ALL video cameras will exhibit this issue in some way shape or form given the conditions stated above. Our jobs as seasoned professional videographers is to recognize the inherant problems of the MEDIUM, and take actions to correct or avoid them in the first place.

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Old August 14th, 2004, 10:58 AM   #39
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I'm no expert but I would like to see this same set up locked off on a tripod it might eliminate a few things like handheld shake or oscilation, image stabilizer etc. The red brick in the 25p is too degraded to be moire alone.
Looks like a slightly off vertical movement, blur.
However, THANKS TO CLIVE for taking the time to report this, whatever it is deemed to be.
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Old August 14th, 2004, 11:04 AM   #40
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I don't know how it was shot, bill, but if I had to guess, it looks like the in-camera sharpness was turned way up, and the image was then expanded from the DV dimensions to the 576x1024, and that there was possibly some gain during shooting as well...the image quality of the building just doesn't match any other image I've seen off the camera, including clives other shots...so something is not right.

Barry
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Old August 14th, 2004, 09:28 PM   #41
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What were the settings on the camera? I have no idea if this could be the cause, but.... the XL2's coring function is supposed to help decrease detail thats not importantant to the image... perhaps the corings on to high for those images and it decreased the resolution and added artifacts. I don't think it should do that but its worth bringing up.
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Old August 14th, 2004, 09:34 PM   #42
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Barry or somebody else would know a lot more about this than I do, but my understanding is that the Coring adjustment controls video noise levels in areas of the image containing smooth, even surfaces -- and not in busy patterns such as a brick wall. So I don't think the Coring adjustment would be very effective here. But what do I know; I've never used a camera that had that type of adjustment.
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Old August 15th, 2004, 01:23 AM   #43
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did I see it correctly that you use a composite cable to capture uncompressed? Use YC or component if you can. 10 bit Uncompressed capturing is overkill for composite video. Composite video cables can give you a moire pattern even with the best cameras. Composite cables just don't have the bandwidth and all three channels(Y,U,and V) are smashed down to one channel. This was why YC(S-Video cables) were invented. Their main purpose was to try and get rid of moire patterns and it worked for the most part. Component is even better. Why don't you try capturing regular firewire and see how that looks on your computer. If I am mistaken about you using a composite cable then forget this post. Hope this helps however.
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Old August 15th, 2004, 05:07 AM   #44
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To Rob: Yes will look at that feature.

Yes, will try digitising in using different output although I think it will still be there.

Let me explain. The image showing the moire was deliberately taken adding fields since it was the only way to illustrate and show the moire as seen on the video monitor. The image underneath on the webpage shows what is visible on the TFT screen from FCP. No moire. The image above is showing the closest impression of the video monitor NOT what is in FCP.

Therefore, YES it will show artifacting of other kinds through getting it as a web born image but that was not what was intended to show. JUST the moire. Hence the reason why the Gull and Carousel images were posted to make sure people were aware that apart from the moire, the image quality is superb.

Sorry Barry but I we are definately going to have to agree to disagree. From an aesthetic point of view, I would not blame any DOP who would simply not stand for moire or to be limited by such regardless of the format. But that's the catch. This camera is trying to pretend to not be DV. Its pretending to be something it isn't and many are going to fall into the trap of using it thinking they can get a film without shooting on stock. Not everyone would have your knowledge or understanding but at the same time, people will judge with their own eyes. YES the moire is on the screen, YES it is ugly and NO you do not have to accept it as part of the medium when you want to create a great looking film.
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Old August 15th, 2004, 06:40 AM   #45
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Clive,

Thomas is absolutely right - I hadn't seen that you captured this image in composite. Most of the artifacts are in keeping with a composite image. This is, as you know, the lowest quality of video capture. You need to capture this into FCP as native DV digitally then export it as a still.

It is all very well saying to us that your only concern is the moire, and that's all you want us to look at, but we cannot judge the extent of the moire problem whilst we are looking at far more serious artifacts.

I am a little concerned that you are basing feedback to both the BBC and Canon based on this clearly unrepresentative method of capture.

Best regards,
John.
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