question about d800 -vs- focal length "rule"

[risc32]

I've read that with the d800 you need the best lenses to really reap the rewards of all those megapickles. I guess that's probably true. I've read and seen tests showing it's very good noise performance. Cool. But I've also read that you need to go over the 1x focal length "rule". Something like 2x or i even read 3x somewhere. wow. Is this proving true? It just seems to me that if those new "rules" are correct, i would think that many times i would have to bump up my ISO settings to deal with that. So i could possibly be running a stop or 2 higher than i would using something else. like a 5dmk3 or whatever camera of less resolution. That would really change things. Now that could be wrong and everything is just peachy at 1x focal length. That's fine too. No agenda here. I'm mostly a Canon shooter and I've never thought about swapping. I'm just curious about this stuff.
BTW- I didn't know where to post this. i hope this is a suitable place.

 

[Kernuak]

I've read that with the d800 you need the best lenses to really reap the rewards of all those megapickles. I guess that's probably true. I've read and seen tests showing it's very good noise performance. Cool. But I've also read that you need to go over the 1x focal length "rule". Something like 2x or i even read 3x somewhere. wow. Is this proving true? It just seems to me that if those new "rules" are correct, i would think that many times i would have to bump up my ISO settings to deal with that. So i could possibly be running a stop or 2 higher than i would using something else. like a 5dmk3 or whatever camera of less resolution. That would really change things. Now that could be wrong and everything is just peachy at 1x focal length. That's fine too. No agenda here. I'm mostly a Canon shooter and I've never thought about swapping. I'm just curious about this stuff.
BTW- I didn't know where to post this. i hope this is a suitable place.

I can't comment on the D800 specifically, as I don't own it and am unlikely to (although a work colleaugue has one, so we may do a comparison one day). However, my experience with the 7D and its high pixel density shows that it is much less forgiving of "errors". It does emphasise motion blur that may not have been previously visible and also shows up some of the lesser lenses, so I imagine there will be similar problems with the D800, particularly if you're shooting something which requires sharp corners and the lens falls off badly in the corners. That said, the pixel density of the D800 is less than the 7D, so it probably wouldn't be emphasised as much, apart from the full frame sensor using the worst part (corners) of lenses.