e anche qui
http://www.kenrockwell.com/nikon/d3x.htm
The D3X is a total no-big-deal.
The D3X is exactly the same as the Nikon D3, just with more pixels and much slower frame rates and ISOs. Want to know everything else? See my D3 review; I'll spare you from repeating everything again here.
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Recommendations
There is very little visible difference when you only double the area pixel count (12 MP vs. 24 MP). There is only a 42% increase in linear resolution with the D3X (6,048 pixels horizontally) over the D3 (4,256 pixels), which is barely visible. This means that, all else being equal, that images from the D3X can be enlarged only 42% more, while the D3X has half the ISO at the same noise level and half the frame rate. (see also the Megapixel Myth.)
Since the D3X will have to be shot at one stop slower ISO for the same clean results, the added blur for real subjects shot one f/stop wider (or one stop slower shutter speed) often can give softer results on the D3X. Whoops!
Do you really want to pay a $3,800 premium over the D3 for a mere 42% improvement in linear resolution? Why not buy a D3 for speed and low light, and buy a Canon 5D Mark II for high-resolution full-frame shots for $2,700, and pocket the leftover $1,100 to go party? Very, very few photographers know what they're doing well enough to get this sort of sharpness at the sensor, so for most guys, D3X images will look the same (or worse) than D3 images.
Buy a D700 instead for speed and ease-of-use, or a Canon 5D Mark II if you need ultimate resolution. I'm serious: the D700 handles much better than the D3 if you don't need the frame rate for sports.
I'll let you know when I get my hands on all these for a run-off, but I've already compared the old 12MP Canon 5D against the 12MP Nikon D3, and the 5D is sharper. I suspect the Canon 5D Mark II, with the same resolution as the D3X (21.1 vs. 24.4 MP, only a 7% difference in linear resolution), may very well be sharper than the D3X. Of course the Nikon should have far superior ergonomics, but weighs about twice as much.
If you have the cash, by all means go get a D3X, but realize that the only time you'll notice the resolution difference is printing 20x30" (50 x 75cm) and larger, and then only if you have almost perfect lenses and really know how to use them.
$8,000 also buys a lot of film if resolution is your only interest.
See "Is It Worth It" for more.
If you don't have the cash, I wouldn't rush out to get a D3X for $8,000. I would if it were priced at correct market value, which is $5,500. I'll bet you prices will drop fast as Canon and Nikon try to eat each other's lunch.
Is the "X-Factor" worth $3,800? Not to me! With unlimited cash I'd get a D3X just because I could, but for most subjects, most situations and most photographers, the D3's superior speed and sensitivity are far more important than adding more pixels. I have great 20x30" (50x75cm) prints sitting here made on my 6MP D40, so no one's going to upsell me for $3,800 just to get more pixels at the expense of ISO and frame rate to do what I already do.
