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Old 08-19-2008, 01:23 AM   #1
MidEngine4Life
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I was doing a little experimenting with my camera today and took this minute long exposure. Can anyone tell me wtf is with all the little pixels? Is my lens dirty? Is my camera dying?
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Old 08-19-2008, 01:31 AM   #2
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first problem, you did a "Save for web" which killed the exif data... so no idea what camera you are using.

Second, it looks like your camera has some pixels which are over active when stimulated in long exposure for misc. values.

On my 20D, I had 4 or 5 pixels which did this, but always in a light grey value, not misc. RGB's like yours. I don't think your camera is dying, unless perhaps it is some upper model Canon or Nikon or something.

I think the technical name is "dead pixels" but its not the most accurate name, since it only happens on long exposure (same as when my 20D had the grey pixels.... which were only noticeable when flipping from one image to the next.)
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Old 08-19-2008, 01:48 AM   #3
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I just have it set up to save as jpg. Next time I do a long exposure do you think I should set it so save as a raw file?
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Old 08-19-2008, 02:00 AM   #4
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Originally Posted by MidEngine4Life View Post
I just have it set up to save as jpg. Next time I do a long exposure do you think I should set it so save as a raw file?
no, that shouldn't make any difference. I'm just curious what camera/lens/settings etc. in the exif data.

when you resized the image, were there fewer "HOT pixels" ?
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Old 08-19-2008, 02:04 AM   #5
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Yea in its raw large size before i resized it there were a lot more visible. Im using an Olympus E-500. I was using the "S" setting that lets me select the shutter speed while it compensates for the rest. Set it at the max of 60 seconds.
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Old 08-19-2008, 02:12 AM   #6
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Originally Posted by MidEngine4Life View Post
Yea in its raw large size before i resized it there were a lot more visible. Im using an Olympus E-500. I was using the setting that lets me select the shutter speed and it compensates for the rest. Set it at the max of 60 seconds.
OK

what is happening with long expsoures is the CCD ends up heating up, and more pixels become "hot" and expose in misc colors.

60 seconds is a LOT of expsure time. Tolerences change in mfr. spec with the more exposure time you have there is less mfr. spec for hot pixels... i hope that makes sense.

that said, the number is pretty outrageous IMO... seems you aren't the only guy with this issue

http://photo.net/olympus-camera-forum/00LYDX

In my canon, there is an option for "color noise reduction" on long exposure. It's already so low that I don't have this set on, even in bulb shots of 200 seconds (i've only done that a few times) ... where basically the software compares the noise in a normal exposed shot compared to the long exposure, and eliminates most of the hot pixels that would form.

so a bit of PS will solve your issue... but unfortunatley, it does seem normal
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Old 08-19-2008, 03:37 AM   #7
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would be a bomb photo minus those, as nth calls them, hot pixels
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Old 08-19-2008, 03:59 AM   #8
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Just dunno how to PS those out without using the clone tool on all 5 thousand of them lol
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Old 08-19-2008, 04:03 AM   #9
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You just need to take another picture. There's no other way than that.

So, was that in the middle of night or what? Minute long exposure must be insanely tedious.
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Old 08-19-2008, 04:27 AM   #10
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It was shortly after sunset.I really need a new camera.
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Old 08-19-2008, 04:45 AM   #11
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^What'd you do to fix it? Clone?
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Old 08-19-2008, 04:46 AM   #12
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Filter: Noise: Median + Clone + Resize
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Old 08-19-2008, 04:49 AM   #13
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Okay then. That works.
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