The Nikon D3x was a very impressive full-frame DSLR when it was first announced, but it can't really compete in our lab tests against its more modern rivals.
The difference between its signal-to-noise ratio and dynamic range scores reflects the technological developments that have taken place since December 2008, when it was originally released.
The Nikon D600 and Nikon D4 produce particularly impressive results at the lower sensitivity values, but it seems that Canon has tried to achieve a more consistent performance across the entire sensitivity range with its cameras.
Not surprisingly, given its huge pixel count, the Nikon D800's signal-to-noise ratio and dynamic range scores take the most dramatic dip at ISO 160 and above.
Spend £4,850/US$6,800/AU$7,300 on a camera body and you expect something special. The Canon 1D X has "special" written all over it. Handling, image quality and build quality are all superlative.
The 18.1MP resolution and dual Digic 5+ image processors deliver a class-leading drive rate of up to 14fps, along with spectacular low-noise performance even at very high ISO settings. This makes it our top full-frame DSLR.
However, the Nikon D4 runs a very close second, and at £4,250/US$6,000/AU$6,700 is cheaper to buy. Both cameras are excellent all-rounders, even if they don't rule the roost when it comes to image resolution in this test.
If you want ultra-high resolution, the 36.3MP Nikon D800 is a natural choice, but you'll need the very finest lenses to do full justice to those extra megapixels. The older D3x is past its best, and has relatively poor high-ISO performance.
The most affordable full-frame cameras are the Canon 6D and Nikon D600. We prefer the D600, with full-coverage viewfinder, more advanced autofocus, pop-up flash with wireless command options, and dual memory slots, even if it lacks the 6D's built-in Wi-Fi and GPS.