Canon's introduction of the 1D X had to prompt a response from Nikon, and now we're hearing the first rumored spec sheet for what that might look like. Nikon's D4, the subject of whispers and speculation for most of this year, will reportedly feature a 16.2-megapixel sensor, an 11fps burst mode, and a native ISO range of between 100 and 102,400. That doubles the 1D X's 51,200 default maximum ISO, but there's an expansion option that can crank things up to the wild heights of ISO 204,800 (the 1D X is capable of that too, through its own extension mode). These numbers hardly sound credible, but having witnessed the amazing performance of the Nikon D3s at ISO 12,800, we're willing to believe Nikon can deliver useful images even at the extremes quoted here. Part of that achievement will also be down to keeping the pixel count soberly in check at just over 16 million.

Other improvements over Nikon's current top-of-the-line cameras include compatibility with CompactFlash XQD memory cards, an integrated Ethernet port, and unspecified tweaks to the 51-point autofocus array and video. The cross-type autofocus points are down to nine from the 15 on the D3s and D3x. This is all still speculative information for now, but Nikon Rumors has a good record of unearthing the facts ahead of release, so we wouldn't be surprised if the eventual D4 specs turn out very close to what we're seeing here. Now that some actual numbers are slipping out of Japan about this new camera, it also looks likely to debut alongside the long-awaited D800. Should make for a fun January in the photography world.