It is probably my favourite lens (used on D500 and D850), very sharp, takes 1.4 tc very well, focuses quicker with the mkIII version. I try and avoid getting it too wet but I have never had an issue with the weatherproofing. Focus is fast about the same as my 500pf, probably a hair slower than my old 500 f4 and very slightly slower than my 70-200 f2.8. I find it a brilliant lens for travel so small and light, I use it with the 1.4 tc about 50% of the time without hesitation, also a good combination for skittish insects. I have used it with a canon D500 close up lens and this makes a reasonable alternative to a dedicated macro lens when I want to travel light.
