I have a 5DIV which I love, but I need a second body to save me changing lenses so much at Air shows. In this scenario my primary lens is a Sigma 150-600, but I'll often need to use my 70-200 F4 is at very short notice when aircraft taxy past on the ground. The other situation where I need to use both lenses is at arrivals/departure says when there is a mix of very large and very small aircraft taking off alternately.
I was going to buy a 6DII for this purpose, but the thought of having a smaller body which I could also make use of with my children or on holiday is quite appealing. I realise that the Sony 70-200 is also a great lens, but I would prefer to keep the Canon because I love it and I would have the flexibility of putting it on the 5DIV.
My question is, will the A7II with a decent adapter and the latest firmware cope well with tracking aircraft taking off? I wouldn't try to track a fast jet display with this system, but I couldn't handle it being very hit and miss on the relatively easy stuff.
Sorry to be so long winded! Any thoughts would be appreciated.