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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 January 29th, 2007, 02:44 AM   #1
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Getting rid of noise

I know alot of people have mentioned this, but this weekend I finally had some time to try my XH-A1 in daylight.
I shot to tape, turned AGC off (was the first thing I did when I got it), set gain to -3db and tried all the 18 presets here.
Not one of them gave me give the results that I saw some of the clips posted here. I keep having some noise/grain in my pictures.
Can someone maybe tell me how they did it in their clips. Cause I bought the XHA1 based on the clips I saw here, and it is really frustrating when I can't get the same results. Or is the noise-reduction some post-process?
I searched the forum but couldn't find a real answer to my problem.
I'll see that I post some clips later on.
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Old January 29th, 2007, 03:25 AM   #2
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You shouldn't have much noise at all in daylight, only small microscopic grain, that is more abundant when you look for it. What was your aperture at? Some times at 6.0 or higher you will get grain. As far as any other explanation, the A1 is pretty clean at -3. I would never say that I have been concerned about grain, it is minimal and irrelevant to the other things I worry about; like DOF, exposure and focus (while I am shooting).

Sorry, I cant help much, someone may bring you solice though.
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Old January 29th, 2007, 08:29 AM   #3
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Which program mode was the camera using?

AGC is always on, even if it's switched off, in "Green Box" (easy record) mode.
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Old January 29th, 2007, 08:57 AM   #4
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Just buy the camera too, and made some tests this weekend, and have the same issue with noise, so I have the same frustrations as you. Perhaps it is the current bad weather in belgium ... my camera was set on manual with no gain and no noise reduction settings on.
I will make more test this week but it would be great to know how to achieve the good quality as the clips posted here.
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Old January 29th, 2007, 06:04 PM   #5
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Since you're bith in Belgium, maybe there was something wrong with the batch of A1s that Canon shipped there.
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Old January 29th, 2007, 06:31 PM   #6
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Noise can be introduced by underexposing your picture so be careful that your exposure is correct. Sometimes you have to make a trade off by blowing out some sky just to correctly expose your foreground and midground.

Going automatic to any degree is not recommended although you may not have a choice at the beginning when you are still learning.

So, in summary, I find that if I underexpose any camera, no matter what the make, noise is a problem to some degree.

Anyway, just another thing to consider.
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Old January 30th, 2007, 06:39 AM   #7
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I always shoot in manual mode. I'll check my camera this evening to see what all the settings were. I remember shutter was 1/50
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Old January 30th, 2007, 07:57 AM   #8
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can anyone take a still from the video and put it up for us to see?
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Old January 30th, 2007, 10:04 AM   #9
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Ok I test it some more this afternoon in my garden, and there is a lot of noise a 0db and -3db (don't ask about more gain ...), even with bright (cloudy) sky.
If I underexpose, the picture is very ugly. no deep black, I post a picture here.
but It look a lot beter (at -3db and 0db) with NR1 on low.

1/50 4.2 0db
http://img227.imageshack.us/img227/6295/420dbyf0.jpg

1/50 3.7 -3db NR1
http://img242.imageshack.us/img242/7397/373dbnr1yq2.jpg

1/50 7.3 0db underexposed... ugly
http://img242.imageshack.us/img242/2792/730dbhe7.jpg
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Old January 30th, 2007, 12:31 PM   #10
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I made a clip available:
http://www.banapsis.eu/downloads/Noise.mov

And here are a two stills:
http://www.banapsis.eu/downloads/still.JPEG
http://www.banapsis.eu/downloads/still2.JPEG

My settings were:
Shutter: 1/50
Aperture: f/9.5
Manual control
AGC off
and I went through the presets here on dvinfo.

PS: I just saw that in firefox the images are really dark.
I'm working on a Mac and on my screen it all looks bright (and also on viewfinder it looks bright). I captured it all in iMovie. (am saving money to get FCP)
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Old January 30th, 2007, 12:57 PM   #11
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Quote:
Originally Posted by Jeremy Naus
I made a clip available:
http://www.banapsis.eu/downloads/Noise.mov

And here are a two stills:
http://www.banapsis.eu/downloads/still.JPEG
http://www.banapsis.eu/downloads/still2.JPEG

My settings were:
Shutter: 1/50
Aperture: f/9.5
Manual control
AGC off
and I went through the presets here on dvinfo.

PS: I just saw that in firefox the images are really dark.
I'm working on a Mac and on my screen it all looks bright (and also on viewfinder it looks bright). I captured it all in iMovie. (am saving money to get FCP)
Why f9.5 ???

With the iris that closed you'll run into softening of the image by diffraction. I have looked at the video and you are well under exposed. You have to make a creative decision to expose for the car and garden risking blowing out the sky or exposing for the sky and under expose the car.

Be familiar with signal to noise ratio SNR. If you under expose your signal will be low and in amongst the baseline noise of the camera a low SNR. By correctly exposing a scene you increase your signal away from the noise increasing your SNR. Learn to expose a scene properly will keep you away from noise reduction settings. Only use then as an absolute last resort.

A way to shoot a dark garden and stop the sky blowing out would be to use a graduated ND filter.

TT
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Old January 30th, 2007, 01:39 PM   #12
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Is there someone who owns an A1 PAL version, and has no problem with noise?
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Old January 30th, 2007, 02:24 PM   #13
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Quote:
Originally Posted by Stefan Koler
Is there someone who owns an A1 PAL version, and has no problem with noise?
Absolutely. With the kind of weather we're having now in Poland, I'm shooting at 0 dB; no visible noise. A couple of days ago we had snowy landscape and sunshine, so I went down to -3dB - even better!
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Old January 30th, 2007, 02:30 PM   #14
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Quote:
Originally Posted by Piotr Wozniacki
Absolutely. With the kind of weather we're having now in Poland, I'm shooting at 0 dB; no visible noise. A couple of days ago we had snowy landscape and sunshine, so I went down to -3dB - even better!
How do your shutter speed and aperture settings compare?
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Old January 30th, 2007, 03:16 PM   #15
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Quote:
Originally Posted by John F Miller
How do your shutter speed and aperture settings compare?
Well, I'm trying to operate around the sweet spots of both the zoom (some 20%) and Iris (4.0-5.6) whenever possible, so when I see the exposure calls for iris of >7.8, I engage the ND filter and/or decrease gain to -3dB, if still possible. Shutter speed I'm trying to keep constant at 1/50th (I leave 1/25th for lowlight conditions, and faster speeds for special action situations). BTW, it's my favorite to shot in the "semi-manual" of the TV mode, which takes care of the exposure but leaves me the freedom to change the aperture manually (eg. for DOF effects) whenever I want, by simply pushing the Exposure Lock button whereby the Iris ring becomes active...That's my general rules, I guess.
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