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Old Jan 20, 2004, 4:45 PM   #1
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Posts: 232
Default Hot pixels - Is my camera defective?

Shutter priority mode.
ISO 50.
Shutter speed 8 sec.
Burst mode - this is important!

Covered the lens with the supplied lens cover - held it tight against the lens because it will not attach when the lens is extended.
Clicked the shutter release button - the camera took just one picture because the button was not held down.
Because of the burst mode, dark frame substraction was not done.

Viewing the taken picture on the LCD at 16X magnification showd a very large amount of colored dots (mostly blue, some red) - up to 10 per screen in some areas.

Is that normal?
I mean, several hot pixels at long exposures can be expected but that many?

2nd experiment:
Repeating the procedure, this time at ISO 400, resulted in a lot of noise in addition to the hot pixels. The noise was more fine and more uniformly distributed than the dots.

Fellow zoomers, can you repeat this experiment and post your findings?
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Old Jan 20, 2004, 7:25 PM   #2
Join Date: Oct 2003
Posts: 96
Default Hot pixels and warm pixels

My FZ10 does the same thing, but I think it's due to "warm" pixels, not hot ones.

Try setting the camera to 1/1000 second with the lens cap on in a dark room, then take one frame of a burst (to prevent dark-frame noise reduction), and examine the result. If you see any very bright pixels, they're "hot" (always on). But, if you have to use a relatively long exposure just to be able to detect non-black pixels, they're just warm (more sensitive than most other pixels).

The test that matters, of course, is whether you can detect any warm or hot pixels in an actual photo. I have an older digicam that has one green hot pixel. I didn't notice it until I'd used the camera for 8 or 9 months. Looking back through photos, it was in every image, and is in every image taken since (almost 4 years of photos). But, when not hunting for it, I've only actually noticed it in maybe 3 or 4 pictures out of the 5000+ taken with that camera, and then, only on the screen when doing magnified touchup for some other purpose. It's never been noticeable on a print.

I've already taken close to 6000 pictures with this FZ10, and haven't noticed any hot or dead pixels, even though I've looked for them. I do know it has warm pixels, including an elliptical area towards the upper-left side. But that only showed when I pushed "Levels" from "255" to "4" on test images of the lens cap in a dark room; it doesn't affect real pictures.
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