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Old Jun 3, 2006, 7:06 PM   #1
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Mostly green, but also some blue and red speckles, not noise, appeared during a F32 30 second exposure. ISO was 100. These are not visible untill viewed at 100%.

They are not there at 25 seconds or less.

Hope I'm not pushing those little pixels too hard and possibly doing damage?


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Old Jun 3, 2006, 8:01 PM   #2
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You're kidding, right?:roll:
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Old Jun 3, 2006, 8:29 PM   #3
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No, not at all.

This pic fails to show 'em I guess.

What could they be? A 30 second exposure sounds pretty odd for starters, but that aside. I'm guessing you think its just a type of noise and thats that? I know long exposures lead to noise at any ISO, and that 30 seconds is probably rediculous.

Lay it out for me.





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You're kidding, right?:roll:
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Old Jun 3, 2006, 9:00 PM   #4
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I was talking about the pixel damage part:G
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Old Jun 3, 2006, 9:54 PM   #5
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OK, can't say as I ever heard of frying a pixel.

Still, it seemed weird. Up to 25 seconds all was well then wham at 30 seconds.
Am I seeing overly excited pixels that are going to fully recover?

Bottom line then, it ain't hurtin anything except for 100% crop?

Thanks for helping Nooner, Tazz
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Old Jun 3, 2006, 11:35 PM   #6
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Tazzie wrote:
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OK, can't say as I ever heard of frying a pixel.

Still, it seemed weird. Up to 25 seconds all was well then wham at 30 seconds.
Am I seeing overly excited pixels that are going to fully recover?

Bottom line then, it ain't hurtin anything except for 100% crop?

Thanks for helping Nooner, Tazz
OK.... whay are you shooting that requires a 30exposure


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Old Jun 4, 2006, 10:29 AM   #7
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I was messing round with seeing the depth of field I could get with dark objects in a short space, maybe 10 inches. Eventually I got to F32. The FZ20 never allowed F32. It was dripping with depth of field anyway. It wasn't that anything other than curiosity required 30 seconds, except F32 and black objects illuminated with 100 Watt Quartz.

Cropping accentuates the speckles which are evenly distributed throughout the picture randomly. Unlike noise they are not blotchy smears of color, nor do these speckles or dots of primarily green appear more in the less exposed areas as noise does. There are blue and red too, but they are easily missed.

On this site they are much less easily seen and appear white for whatever reason. Unless a crop is vewed they are not discernable.

I would expect this would be a real problem for those using a 5 and maybe 7D for astronomy.


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Old Jun 4, 2006, 10:40 AM   #8
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The last photo above is sharpened as is the original below.

This post was an FYI hoping for a good comment as to why this jumps in at 30 seconds and is completly gone at a shorter period. Beyond that, if in fact its hard on the camera at all.

Really Hot Pixels??


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Old Jun 4, 2006, 11:21 AM   #9
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Virtually all digital cameras will have hot pixels on longer exposures. You just don't see them because most modern digital cameras have a noise reduction system that looks for them and maps them out on exposures of around 1 second or longer (replacing them with values interpolated from adjacent pixels).

The longer the exposure, the less effective this kind of system will be.

I haven't tested it. But, I've seen comments that the Noise Reduction System in the KM DSLR models only works on exposures up to 30 seconds.

If you want to see hot pixels on exposures shorter than 30 seconds, too; try turning off Noise Reduction. ;-)

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Old Jun 4, 2006, 12:44 PM   #10
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Jim, I've always kept noise reduction off.

I barely see them in a sharpened 25 sec crop and their gone completly at 15 seconds.

Its not what I'd call normal noise though.

Jim, do you consider that hard on the camera atall?

Never been shy about exposing my ignorance if I can be illuminated.

Thanks Nooner and Jim.
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