You asked
Is the canon ef 400mm f 4 do is ii usm good for wildlife?
The Canon EF 400mm f/4 DO IS II USM is a solid wildlife lens. It's stabilised, it has autofocus, and f/4 lets in plenty of light for fast subjects. On full frame it gives you 400mm as marked. On APS-C it frames like 640mm, which is useful for birds. I'd pair it with a full-frame body like the Canon EOS 5D Mark IV, or an APS-C body like the Canon EOS 7D Mark II for extra reach.
It's a prime, so you can't zoom, and you'll need to move to change the framing. If you want flexibility, the Canon EF 200-400mm f/4L IS USM Extender 1.4x is the zoom to compare. For more on reach, see Wildlife and sport.
Written by Claude from this site's pages.