They are fun to shoot. I've shot hundreds of pics of them this year. Here is a tip for you to catch one in a natural environment. Find a flower that they like such as a basket of petunias and hang it close to the feeder. Then when you get ready to shoot, mix up some of their food and put it in a spray bottle. Lightly spray the inside of several of the flowers on the plant. Trust me they will find the "nectar" that you added to the flowers. It may take some patience but you can get some great shots this way.
Thie pic I attached was with my 5d MkIII, 100-400L lens. Shot at 400mm, 1/640 sec @f/8.0, ISO 400. The picture is cropped to about half of its original size.
Mine is with a 5D3, 70-200 IS II at 200mm, 1/2000 sec F3.5, ISO1000.. It is cropped at around 1/6 the size (sorta.. it is very cropped)
What kind of autofocus do you use? I was using 9 point zone AF in AI Servo but it was hard
most of my shots were out of focus, and the hummingbirds would move so fast...
All point AF was impossible, it was supposed to start with the single center point and start tracking from there.. but it would, just, not, pick up the bird...
I was also using the "case 5" AF.. for erratic subjects moving quickly in any direction.