Here's another one with the 100-400mmL. This shot was taken on a tripod and it took several attempts to get a sharply focused image. This is a nearly 100% crop also and the subject must have been 100 meters or more away. It was also breezy. I used live view, magnified the image 10x, and manually focused to get this one. Luckily, there was lots of light.
400mm, f/10, 1/1000, ISO 400