Originally Posted by
carregwen
The camera should not normally make much difference to HDR processing.... but.... your old camera was 10mp which had a pixel density of 3mp cm2. Your new camera (we call it the 500D over here) is 15mp with a density of 4.5mp cm2. The sensors are the same size, so the pixels are smaller, which means they are less efficient at gathering light, which means more noise. The new processor in the camera and its in-camera software will mitigate some of that difference - but who knows? I have a 50D which is same sensor size and pixel rate, and I would say it's border-line when it comes to noise. Now, the 5D, which I also own, is a different story.
Can you post one of the shots? If you still have the old camera take the same shot with the same lens, on a tripod and compare the RAW output to see if there is any discernible difference.