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Author Topic: hot pixel or dust?  (Read 2689 times)

lowep

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hot pixel or dust?
« on: April 24, 2010, 12:47:03 PM »


Do you have any idea about how to tell if a constant white spot on a camcorder image is caused by dust or hot pixels - or both?

A few days ago I started noticing a small white spot in the same place in every frame of recent footage (see attached image) shot with my Canon XM1 miniDV camcorder. It appears on both the LCD and my computer monitor. It is not very bright - when I put the cap on the camera and zoom in and out I can barely detect it. But it is easy to see on recorded footage. Would dust on the lens or the sensor show up as a white spot or a dark one?

Now there seems to be more than one.

Maybe they are breeding?
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Eric Myrvaagnes

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hot pixel or dust?
« Reply #1 on: April 24, 2010, 07:54:11 PM »

I don't have a camcorder, so my opinion may not be worth much. But I've seen lots of sensor dust on my Canon 5D (worst was from photographing in a dust storm at White Sands, New Mexico -- hey, the camera's a tool to be used, right?).

All of my sensor dust has seemed much bigger and with much softer edges than your spots, and always dark, not white, so I suspect hot pixels. And when I enlarge your sample image, I see fine horizontal lines which look like scan lines (?), and your white specks seem to be consistently the same height as the distance between two 'scan' lines.

If your camera is still under warranty, I'd take it back for service or replacement. That's my take on it, but I hope someone with camcorder experience will chime in on this.

Eric

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francois

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hot pixel or dust?
« Reply #2 on: April 25, 2010, 03:11:51 AM »

I would agree with Eric's diagnostic. Dust spots are mostly dark/dark color. I've yet to to a white/light colored one. White hot pixels have been reported on JVC camcorders, but, IIRC, that was a couple of years ago.
You'l probably have to send in your camera for service.

You could also try to post on specialized camcaroders forums or ask Chris Sanderson if he has an opinion on your issue.

 
« Last Edit: April 25, 2010, 03:14:46 AM by francois »
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Francois

Chris Sanderson

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hot pixel or dust?
« Reply #3 on: April 25, 2010, 09:20:43 AM »

It certainly looks like a sensor-related issue and not something physical. I too believe Eric is right.
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Christopher Sanderson
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Eric Myrvaagnes

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hot pixel or dust?
« Reply #4 on: April 25, 2010, 09:34:18 AM »

Quote from: Chris Sanderson
It certainly looks like a sensor-related issue and not something physical. I too believe Eric is right.
I guess now I can proudly consider myself an expert on camcorders! And I can be totally objective, too, since I have never used one.    

Eric (One frame at a time is enough for me.)


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lowep

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hot pixel or dust?
« Reply #5 on: April 25, 2010, 10:35:54 AM »

thanks for the useful replies
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