You should look at this Thread: "Use IS or not use IS" I've posted a bunch of post on the DOF an long lenses. As your point of focus on the first photo is the bird and the lens id at low F stop the background is not in focus but the bird is. On the second photo the AF focused on the power lines and again the background is out of focus.Originally Posted by MaorG
Having a 10 or 12 X zoom means that at the telephono end the DOF is very shallow. With equivalent focal length of 200mm, F set at F4, Focus set at INF, near in focus point starts at 3282 feet, if your focal point is at 100 feet in focal range or DOF is 97.1 to 103 feet. Using a higher F stop helps, 200mm, at F32 DOF is 80.5 to 132 feet.