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  #21  
Old 29-11-2013, 08:22 AM
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Quote:
Originally Posted by Carl View Post
Hi Terry
Hot pixels are easily defined and removable. My image is just covered with red and blue dots tat don't look like they have a sharp edge. These dots are in the exact same position on all 20 images, surely it can't be random noise. I have no idea what they are. The guy from Canon suggested that it was acceptable noise, i find that hard to swallow on a camera that has been given a lot of hype about low light sensitivity.

I just did the same exposure test tonight shooting both RAW and JPG. The JPG was not too bad, but he RAW was just as bad as the above sample.

I'm in a pickle here.

Regards
Carl
I would have thought that if the noise is in exactly the same place on every image then it should easily subtract off with a dark frame. As you say it isn't random noise. Dark current is not "random noise". It is predictable.
I do not have the camera you have and only have a 40D but do have various CCD cameras.
Even in my cold climate a 5 min exposure will have lots of dark current that causes thousands of hot pixels across an image. If you are taking pics above ~5deg C then they will be very obvious.
Try taking a series of dark frames with the camera of the same duration. You need to cover both the lens and the viewfinder as light can leak in via the viewfinder. Average them and then subtract them from the raw image and see if the problem disappears.
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  #22  
Old 29-11-2013, 09:50 AM
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Good post Terry.

Ed hasn't said whether he stacked the results in Deep Sky Stacker along with
a proper set of dark frames -
which would subtract out all those spots.
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  #23  
Old 29-11-2013, 12:11 PM
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iceman (Mike)
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The point is he shouldn't need to.

Those frames do not look normal for a 6D.

http://www.mikesalway.com.au/dishes-in-long-exposure/
http://www.mikesalway.com.au/long-ex...-the-canon-6d/
http://www.mikesalway.com.au/np101-h...-the-canon-6d/
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  #24  
Old 29-11-2013, 01:33 PM
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Exactly, there's something really wrong with his camera - it should be returned and replaced.
-Cam
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  #25  
Old 29-11-2013, 02:02 PM
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Quote:
Originally Posted by iceman View Post
Interesting. What that seems to show is that there must be something done in camera to reduce the thermal noise before outputing the file as a raw image. There is the physical way that the CMOS or CCD detector can have no thermal noise with such long exposures. Makes the camera not very useable for science images but this is not it's purpose.
I agree there must be something wrong with the camera.
Time to get it looked at by the manufacturer.
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  #26  
Old 30-11-2013, 02:09 PM
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You got a dud. Send it in for a replacement.

Greg.
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  #27  
Old 02-12-2013, 01:41 PM
Carl
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Thanks to every ones input on the issue.
It's going back to the shop for replacement.

Regards
Carl
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  #28  
Old 20-01-2014, 05:34 AM
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Hi Carl

Just following up on this - did you get a replacement?
Is it better?
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  #29  
Old 28-01-2014, 05:37 PM
gazza83 (Gary)
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My new 6D bought in the new year had the same problem as the OP's example. It was Australian stock and was replaced no questions asked. The new one is OK.

Cheers
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