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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 September 6th, 2011, 12:18 AM   #1
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What the #%@& is this and is my camera trash?

So I shot a lot of events and I am shocked to find that I am seeing a lot of white/hot spots on the videos.

The problem is that the spots are not always there, they seem to pop up randomly, though they are more apparent when I use higher gain settings (but not always). It seems to be bigger than a pixel, perhaps a cluster of pixels. It is definitely more apparent when shooting on black.

What is this? Can it be fixed? Can I fix it in post (because I have a lot of footage with it)? Any info would be helpful!

Spots on my Canon XH-A1 - YouTube
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Old September 6th, 2011, 06:39 AM   #2
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Re: What the #%@& is this and is my camera trash?

Since the spots aren't moving around or flashing in and out it almost looks like, I hate to say it, the lens has dust on it. It could be small chips in the glass as well.
First, to try to eliminate what it isn't, check the last media you shot and see if the spots show there. Then, shoot something, anything and check to see if it's there. Eliminate things one at a time. check the lens for dirt, lint or scratches.
Guessing won't solve it. You need to carefully inspect and check previous work and work after that job.
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Old September 6th, 2011, 07:04 AM   #3
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Re: What the #%@& is this and is my camera trash?

If they are popping up randomly they could be 'hot' pixels. I had some appear on my XLH1 a few times, the problem was that I could not see them in the viewfinder. If the work is going to end up on DVD then you probably wont see them anyway, if its for HD work then you will have to work on a solution.

At the time I seem to remember there was some way to get rid of them in the camera (I think you had to turn the gain up and then down again or something). I have not seen them in any of my footage for some time though.

There definitely are ways to deal with them in post (in After Effects it should be easy enough). Essentially you need to select pixels bordering the hot pixels and clone them to cover them up.

There are also some plug-ins that can automate this for you. There are a number of them available for purchase, for instance 'Refill' by Revision FX is tailored for this type of work (it works with Premiere, After Effects, and Final Cut). I'm sure there are others out there.

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Old September 6th, 2011, 08:39 AM   #4
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Re: What the #%@& is this and is my camera trash?

Thanks for your help!

The last event I taped I did not see any spots. I shot with 0 db and really watched the screen to see if I could see any spots. I did not. The spots seem to come up random but the same ones come up when they do show up. The time, before the last time I used the camera, some of them did show up. Very FRUSTRATING!

I can see the biggest dot, on the lower left, even on the DVDs, HD it is very easy to see, so it is a problem I need to fix, since most my projects I do put the footage on Blu-ray discs.

I check the outside of my lenses ever time I use the camera for dust, lint... They seem very clean on the outside and even in the inside, from what I can tell see looking in.
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Old September 7th, 2011, 01:09 AM   #5
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Re: What the #%@& is this and is my camera trash?

Hi

I also sometimes have had this problem with bright white pixels showing up. They will definately show up when I'm using high gain settings. Using low gain settings they don't show up so the pixels are probably only "half dead". For me it's not a problem as I very seldom film objects in dark environments so I might have bright pixels without knowing it as they cant be seen on bright scenes.

I once had the camcorder sent in for service and asked them to check the bright pixels but they could not find anything. On the service note there was a description about some kind of adjustment done and when the camcorder returned from service, the bright pixels were gone.

Regards,

/Bo
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Old September 7th, 2011, 12:00 PM   #6
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Re: What the #%@& is this and is my camera trash?

Are you sure it is just not a dirty UV filter or Lens?
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Old September 7th, 2011, 02:12 PM   #7
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Re: What the #%@& is this and is my camera trash?

Greg,

I do not have a UV filter on the camera, plus I check pretty much ever shoot to ensure the lens is clean. Looking from the outside, the inside of the lens looks very clean as well.

Unfortunately, I do not think the problem is a dirty lens, at least from what I can see.

I sent in the camera to Mack, as I do have a Mack warranty on the camera, it is on its last year!

I will keep you all posted what they say.

Thanks
jeff
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Old September 8th, 2011, 05:22 AM   #8
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Re: What the #%@& is this and is my camera trash?

The YouTube video says it is gone this AM. So thsi is offerd without benefit of seeign the video and is with respect to pixel problems, not dust problems.

Check the gain settings when the spots are visible. Also ckeck shutter speed.

Hot pixels (pixels with high dark current) become visible when you have high gain settings and a flat dark background. For example, consider a hot pixel that has an out put of 7.5 IRE at 0 dB gain. This is the NTSC black level.of 7.5 IRE and looks black.

Now add 18 dB gain and the 7.5 IRE level pixel becomes 60 IRE, well into the visible range with a dark scene background. Slow shutter speeds increase the integration time for the pixels dark current and will also tend make it brighter relative to its neighbors

Also, hot pixels appearance will not be effected by camera focus settings, while dust/dirt on the lens or filter will be effected.
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Old September 8th, 2011, 08:19 AM   #9
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New link for video spot sample?

You can download the sample video from here:

http://www.twincitiesweddingvideo.com/SPOTS.mp4
(FYI: It is 137 mb, but in HD so you can see the spots)

Sorry, but after some thought, I did not want it on Youtube.

Great news, I found a fix using After Effects that works amazing! I used the "CC Simple Wire Removal" effect under the "Keying" section. The results were simply crazy good! At one point a large spot is on the brides face, very noticeable, but after the fix, it is gone!

I just fixed over a hour of footage.
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Old September 8th, 2011, 09:40 AM   #10
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Re: What the #%@& is this and is my camera trash?

I do a bit of astro photography for fun and one of the things that changes how hot pixels are displayed is heat. As the camera heats up from use hot pixels become more apparent. Noise also increases with temperature.

We do noise correction manually by taking several "dark" frames over time intervals so we can get the noise/bad pixel info for the imager at different operating temps. Those frames are subtracted from the shots of the object of interest.

Anyway, just adding that camera temperature as well as sensor gain will play a part in the bad pixels. Maybe that can help you find a pattern to the problem and minimize its occurrence.
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Old September 22nd, 2011, 11:36 AM   #11
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Re: What the #%@& is this and is my camera trash?

Update:

I shipped the camera to Mack Camera because I had a warranty with them. They sent the camera to Canon. Wait and see I guess.
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Old November 1st, 2011, 01:19 PM   #12
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Re: What the #%@& is this and is my camera trash?

I got the camera back from Mack, works perfect, no spots anymore. So glad I got the Mack warranty, total fixed it, I just had to pay for shipping.
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Old December 5th, 2011, 06:41 PM   #13
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Re: What the #%@& is this and is my camera trash?

Great to hear you had good experience getting your A1 fixed. I too am having the same problem with my A1. I have the Mack warranty and getting ready to send it in. I never had to use the warranty before so I'm curious as to how long it took to get your camera back. Thanks,
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Old December 6th, 2011, 08:13 AM   #14
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Re: What the #%@& is this and is my camera trash?

Mack did a great job, no hassle at all. There tech looked at it and then sent it to Canon to get fixed. It took about a month for me to get my camera back.
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Old December 6th, 2011, 09:08 AM   #15
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Re: What the #%@& is this and is my camera trash?

A month? That sounds like a long time. My experience has been that Canon turns around their pro camcorders in a week or so. (The consumer camcorders not as fast.) But was is dealing directly with Canon. Wonder what others have experienced time wise.
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