With hummers and dark forest birds, I try to shoot with my Lumix 200mm. On my GH6, that gives me a 400mm equivalent. That lens is super sharp and fantastic in low light, as it's f/2.8. I'll often start with my 100-400mm, though, in case the bird is shy. But that lens isn't as sharp.

oh wow, you must be quite close then! amazing! your shots are always so fantastically sharp