Quote:
Originally Posted by Carl
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
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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.