D800E supremely able autofocusing

I went into some old gold mine with a friend who had a Canon 5DII and I had the D7000 then with a SB900 flash with the Asssist Lamp on.  The miner told us there was an ore cart ahead of us in the dark.  I pointed the camera and flash at the area and saw the assist lamp red bars, but no shot.  When the miner turned on his LED flashlight, the camera got a lock and fired off this shot.



Granted it was pitch black in there, but it did a good job considering the darkness.  The flash assist wasn't able to get a reading to unlock the shutter without the miner's light though.  The Canon couldn't fire at all so I don't know what was up with that so he did some light painting on Bulb with it sitting on a rock.

Mack