Originally posted by madbrain These links provide good background information on noise, and good information about some 4-year old Canon and Nikon cameras.
I'm just not sure how much of it applies to the current crop of Canon, and released and unreleased Pentax cameras
Technology changes, physics doesn't
You're right, we don't know how the current cameras stack up but my guess is that they are more similar than different when it comes to the noise floor. All sorts of systems, ranging from audio recorders to all kinds of broadcasts have essentially had the same S/N ratio for quite a while. There is a technological reason behind it but mostly it's because it generally isn't worth the effort to chase down those last bits of info buried in the noise. The vast majority of pictures (especially from low to mid level cameras) are rendered in 8 bits, and they look great. It would be nice to see more measurements of the new cameras but I have a feeling that other practical things like SR, ergonomics, and focussing have a lot larger impact on the image quality.