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02-26-2010, 12:14 AM   #1
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Long exposure leaves blue and red dots?

I was messing around with my camera tonight and took lots of long exposure shots (was playing around with an LED in front of it) and noticed that in many of the shots I have blue, red, and green dots in the EXACT same spot in multiple pictures. Camera was tripod mounted. Exposures were anywhere from 15-30 seconds each. I have never seen this before on any of my other cameras. What is it and how do I prevent it?

Attached is a picture of it. Hopefully you can see it even tho the picture quality has been downgraded with the upload. It's much brighter on the original.

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02-26-2010, 12:32 AM   #2
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Dead or hot pixels. Run the Pixel mapping routine. Should take care of it.

02-26-2010, 12:57 AM   #3
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Also, were the shots RAW or JPEG? I ask because when I do long exposures I usually shoot RAW, and until they're processed, they're always covered in the spots of which you speak. They vanish once I've run it through CameraRaw or similar.
02-26-2010, 02:13 PM   #4
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These were shot in RAW. I imported them into Aperture 3 and that is where I saw them. Thanks for the replies and suggestions.

02-26-2010, 04:44 PM   #5
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Also, make sure that "long exposure NR" is on in the config menu. I know it has that in the K200 and K20 so I doubt got rid of it on the K7
02-26-2010, 06:46 PM   #6
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Those are hot pixels which actually present at any ISO, but more obvious as the ISO gets higher. I don't know about other brands, but hot pixels are rather common with Pentax DSLRs. If you shoot RAW, most converters will remove them automatically.
02-26-2010, 07:15 PM   #7
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I've noticed some in my long exposures as well. Not quite as many as yours though . . .

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