If that's shot with your L-glass, you certainly can do better sharpness-wise... ;)
The bee was about 8 metres away and the lighting wasn't brilliant
likewise with the bluetit.....much cropping has occured
I'm still learning...it's a very light hungry lens, which isn't a problem on a nice sunny day when the subject is nicely illuminated, but in the dark it gets very shaky at 400mm, especially considering it goes a little soft over 300 anyway