"We've had a chance to prepare a set of full-resolution studio-based JPEG samples from a pre-production Canon EOS 5D Mark III, at all available ISOs from 50 to 102,800. We've chosen to shoot under low level halogen lighting, which provides a stern test of the camera's sensor and noise reduction systems. Note that these samples are not intended to replace, or even be comparable to our standard studio tests, which we'll publish as usual when we get our hands on a production camera.
At a colour temperature of about 3000K and low light intensity (approx 3 EV), these images are also neutrally white-balanced. This requires extreme amplification of the blue channel (and to a lesser extent the green) relative to the red, accentuating any noise or banding that might be introduced by the camera. This should therefore be considered close to the worst-case scenario - under many situations you'll see less noise at high ISOs, for example when shooting indoors in daylight. Also remember that this is a pre-production camera, so may not be entirely representative of final image quality."