Sar - two fantastic shots!
The crop of #1 is a beautiful shot and the detail of the crop in #2 certainly highlights the quality of the lens.
My limited experience with this lens (on a D3200) suggests that dynamic focus is a must for BIF and that f8 (if possible) is the way to go.
I note that you have VC off for #1 - I have read a lot of different opinions as to whether or not to use VC at higher shutter speeds - I think you have settled that question in my mind.
What distance would you estimate these shots to be taken at?
Cheers