Not a huge difference, though real world frames seem to say otherwise in some reviews. The main difference I can see here is the moire, where the D800 fails miserably. Personally, losing that bit of sharpness for less moire probably cancels out the difference. That and I don't have to invest in new lenses.
Thank you. That gave me a good laugh...
Just compare the lines at the left of the frame and the sharpness of the numbers all over the frame...
This is a resolution test, you're talking about acutance, which is a different aspect of what people call "sharpness".
Yes, the D800 has better acutance than the 5D3, but that can be easily fixed in post (a convolution sharpness filter seems to be the best option). Resolution is quite similar, and actually I would rather take the cleaner image of the 5D3. With the DR of the Nikon, but with all the goodies that the 5D3 will soon get thanks to the Magic Lantern people.
And please don't mistake me for a Canon fanboy, I'm one of those complaining endlessly in these forums about the silly price of the 5D3: it should be $2800, it's definitely not worth more than the D800.
Indeed. And the in-camera AA filter, while reducing moire, also results in a loss of actuance, but when comparing on a chart as above, also increases the perceived resolution within certain constrains. You can see an example of this at 5, 6 and 7 of the diagonal lines.
Additionally, I was referring to the video at 100%, and not the frame-grab above, where the difference in actuance is harder to perceive and both cameras do well (albeit, for 720p).
To be honest, all this Nikon vs Canon stuff is a bit petty, in my opinion. There were days before the internet when this kind of blabber was constricted to club meetings; the rest of the time, people were using their equipment, not comparing it.
If you have invested in some stellar Canon glass as I have, get a 5D Mark III and be done with it; if not, get a D800. Lenses are with you for a lifetime, while bodies get changed and replaced in just a few years. Chances are, Canon will be king when the next round of full-frame (or otherwise) cameras are released.