stargazer78 wrote in post #14223658
If the 1DX really is 2 stops better
than the 7D, then it would be the best high ISO camera out there (alongside the Nikon D4 and D3s).
That's true, but it also means that it's on par with the 5D3.
Remember, about 1 1/3 stops of that improvement over the 7D is accounted for by the sensor size alone. That is, if the 1DX used exactly the same sensor technology as the 7D does, it would show a 1 1/3 stop improvement over the 7D on that alone (its resolution is the same as the 7D, so that makes it directly comparable on a per-pixel basis). So that leaves about 2/3 of a stop of improvement due to improvements in the sensor.
But that amount of improvement has already been seen in the 5D3.
The bottom line is that in terms of ISO performance, it appears the 1DX may do no better than the 5D3 which, as it happens, fares no better than the D800 once the resolutions are equalized. So in terms of high ISO performance, it appears all these cameras are pretty much equivalent to each other at a given target resolution, with the only variable being the native resolution.
This raises the very real question of what exactly you're getting for that extra $3500 over the 5D3. We know you'll be getting twice the FPS and better weather sealing (which is of questionable use in practice as even the 1DX will not be covered under warranty in the event of water damage). You'll also be getting a stronger battery with the ability to drive the autofocus of lenses faster, and better battery life to go with it. But it's unclear that you'll be gaining much else.
The next generation of 7D should bring with it a sensor with at least as much improvement in the sensor as the 5D3/1DX, which will once again put it about a stop behind those two cameras.