I always shoot raw and always have these compensation settings turned off. Some people over on dpreview have gone to the bottom to find out why they got some weird banding in their pictures and it appeared to be caused by the lens compensation and shading compensation settings of the (Sony) cameras, even in the raw files. So my advice: if you shoot raw, turn all compensation settings off. Any serious raw editor is capable of applying lens corrections and often will do that automatically.Be sure to turn on lens comp/shading if the body has it, to compensate for vignetting.
Here's a link to the discussions on dpreview. As said, I always shoot raw and have all compensations turned off permanently. I never have done tests for myself to see the difference because I want the camera to mess as little as possible with the raw files, so I cannot present any evidence myself. I just wanted to warn other users for possible unexpected problems.Haven't found any banding on the A9.
Any evidence that fixing vignetting in post is otherwise better than in-camera?
I like this lens also. On APS-C body I can get eqivalent of 600mm full-frame. Thinking also to buy 200-600mm instead of 100-400mm but I just like versatility of 100-400. Decisions, decisions....The longer I use that lens the more impressed I become.
It's fast to focus and relatively compact. It does very well with the 1.4 TC and quite well with the 2x TC in good light and/or enough pixels on the subject. And that gives you a range of 100 to 800 mm.
You can end up shooting at f8 or f11 so subject isolation isn't a strength but BIF are usually fine and AF still remarkably capable.