Hey all,

I am looking to upgrade my gear and was hoping to get your advice as i am having a hard time making a decision and your input would mean a lot.

Currently i am shooting with 7D + 100-400 (the originals), and i have never been happy with the general IQ and AF performance of them but it was just something i was unable to change. I am finally in a position to make a big purchase and since i am not heavily invested so far, and the recent shift of many photographers i am having a hard time deciding if i should jump ship or not.
Another important note is that i am currently planning a lengthy backpacking trip to Australia. (btw if someone has local tips and is willing to share it would be more than appreciated)

My photography is mostly wildlife, mostly large mammals over recent years but would love to get more into birds. I usually find myself on lengthy trips and can involve substantial hiking so my first priority is weight without sacrificing IQ.
I usually try and keep the weight to a minimum for all my gear many times leaving my tripod at home.


It seems to me that the D850 is quite superior to my needs than any other offerings but the lenses on the canon side seem to be a bit more versatile.
it seems like it comes down to 500 PF vs 400 DO II.

some questions:

1) how is the AF on the D850? would it be viable at f/8 for action/bif? how would it compare to the 1Dx-I? 1Dx-II? D5?
(i have read that many times manufactures advertise the same AF system for multiple cameras but don't back that up with sufficient computation/power to have similar performance)
2) how is the AF and IQ of the 500 PF + 1.4 vs the 400 DO II + 2X?
3) it the 400 DO II + 2X viable for action on a 5D IV or would it demand a 1DX body? (the weight reduction is quite appealing)
4) Am i correct in assuming that the nikon AF advantages to maintaining focus on birds with busy background would also hold in situations such as tracking a leopard through tall savanna grass?
5) Also i am not sure how i would replace the versatility of the 100-400 as a secondary lens on the Nikon side. The 200-500 is both too heavy (~1 kg more) and IQ also does not seem quite as good. The 80-400 also looks like is a no go in terms of IQ. maybe the 300 PF + 1.4X? I'm often traveling in harsh environments that make swapping lenses risky so there is a big plus to those high end zooms.
6) Have i completely lost it thinking that packing a 14 mm,24-70, and a 500 mm is viable? :D



Thanks