Noise levels on the Canon 30D remain impressively low throughout its entire range, even at 800 and 1600 ISO. Indeed it essentially matches the EOS 5D up to 800 ISO with its big brother only coming into its own at 1600 ISO and above. As expected, it also comfortably beats the noise levels of the 10.2 Megapixel Nikon D200 and Sony A100 from 400 ISO and above. We wonder how Canon's noise levels will be affected when it inevitably increases the resolution of its APS-C sensors in the future.
Note: we have compared 100% crops from each camera measuring 136x136 pixels. Since the Canon 30D has a lower resolution sensor, its crop therefore represents a slightly larger area relative to the others. That is, any artefacts visible on the 30D crops would be slightly larger and more obvious than the other three if each image was reproduced at the same physical size. In practice though with the models in question, this only makes a modest difference.