You asked
Is the canon ef 400mm f 5 6l usm good on aps c?
Yes, I think it's a good match on APS-C. On a Canon APS-C body it frames like about 640mm on full frame, which is serious reach for birds. The f/5.6 aperture also gives roughly the depth of field of f/9, so more of the bird stays sharp. It's light and focuses quickly, which helps a lot when birds move. The catch is that it has no stabilisation, so keep your shutter speed up.
Good bodies to pair it with from the Canon APS-C list:
- Canon EOS 90D, my pick for most birders
- Canon EOS 80D, a solid, cheaper choice
- Canon EOS 7D Mark II, if you want a tougher, sport-friendly body
If you're shopping for this lens, buying used is worth a look, and my reach notes explain how much reach you actually need.
Written by Claude from this site's pages.