# Blue SPOTS in images.



## Dragonfly..shotz (Dec 1, 2008)

I was not sure where to put this question. A friend took a few night shots and the images have several blue spots in the same location. Does anyone know what may cause this. The camera is a Canon 40D and fairly new. I have had experience with red pixels or hot pixels with mine but the raw converter cleans them up. His were taken in JPEG but i cant help him explain what they are. Any help or redirect the thread would be great thanks.


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## Jaszek (Dec 1, 2008)

If the spots are in the same exact spot in each picture it might be that one of the camera elements has small specs of dust on it. It could be on the front or back of the lens or on the sensor.


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## tirediron (Dec 1, 2008)

I'm going to go with dust on the sensor.


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## Battou (Dec 1, 2008)

Individual pixels are giving out during the exposure. Sensor can't handle the duration, Photoshop is the only sensable option. Clone the dead'ens out and continue on.


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## Craddie (Dec 1, 2008)

If it's night shots where you see it I would say it's hot/dead pixels.  How long was the exposure?  Most cameras have some - comes with trying to jam 12 million of them on something slightly larger than a postage stamp.

Set your camera to F22 or something and take a 1min exposure with the lens cap on.  This will tell you if it's pixels.


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## KhronoS (Dec 2, 2008)

Yeah, dead/hot pixels for sure. I have some of those too )


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## Garbz (Dec 2, 2008)

Everyone has some of those. It's a known fact given a long enough exposure of a high enough gain the sensor will give hot pixels eventually. My camera does it at ISO1600 at 1/10th of a second. Or about after 3 minutes at ISO100.


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## LaFoto (Dec 2, 2008)

My dead pixels can look either blue or red against the darkness of a night sky. They never show with day photography but I do see I got dead pixels on my sensor when I do 30-second exposures at night.


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