This hummingbird suddenly appeared in front of me,very close to the 4.5 meter close-focus limit. I had to take a step backwards to focus. I got off only two frames of him. It was very hard to see the bird and get the camera on him with the 800x1.5 or roughly 1200mm angle of view from such a close range. The 400 3.5's big front element was blocking my view a lot. I shot this hand-held at 1/500 second. Not sure what the aperture is, but it's not wide enough that's for sure. As a grab shot,it has a sort of impressionistic hummingbird feeling.