Is the canon ef 400mm f 5 6l usm long enough for birds?

Yes, on an APS-C body, but only just on full frame. On a Canon APS-C camera the 400mm f/5.6L gives about 640mm equivalent, which clears the 600mm full-frame equivalent I'd call the starting point for birds. A body like the Canon EOS 90D or the Canon EOS 7D Mark II gives you that reach in a light kit.

On a full-frame body such as the Canon EOS 5D Mark IV, 400mm is a decent start, but you will often want to crop. It's light and focuses quickly, which helps with birds. It has no stabilisation, so keep your shutter speed up.

For the reasoning, read reach in wildlife and sport and my picks. Buying used can save a lot; see buying used.

Written by Claude from this site's pages.