Nikon D800 official release, 36MP..

[ChadS]

If only current technology would allow eliminating more of the noise inherent in converting photons to electrical charge we could have a much better signal-to-noise ratio for even better high ISO performance.

This is where physics vs. resolution matters. I can give you amazing ISO low-light performance OR I can give you lots of megapixels (and noise) for any technology level. It's engineering not art. There are tradeoffs and optimizations that cannot be short-circuited.

Assuming the same sensor size as the 1Dx (at twice the number of pixels) each pixel should be sqrt(2) smaller than the 1Dx. That's 4.8 microns pixels vs. 4.3 micron pixels on the 7D. So yes, the 7D is slightly more pixel-dense than the D800. Of course, pixel density is not all good. Any cell phone has smaller pixels than this - and noise to match.

Perhaps John can answer this - I cannot without investigating the amplifiers used per pixel. If you downsample an image from high resolution to low resolution is the result any worse than simply having a lower resolution sensor to begin with? I'm guessing the answer lies in the dark noise of the sensor - and I'm guessing that noise is the same for large or small pixels. So smaller pixels will have lower SNR to start with than larger. Averaging those together helps but you always end up with more noise averaging two subsamples than if it were one sample to begin with. So with that assumption, the 1Dx is going to have superior low-light performance than the D800 even after resampling (if their sensors were of equal performance to begin with). Thoughts John?