The autofocus mechanism in your camera can be fooled by elements in front of your subject that are not part of the subject itself. For example, the grasses in front of the lion can cause the camera to focus on them rather than on the cat. One way to deal with this issue is to turn the AF function off and focus manually. Another approach is to aim the lens at a part of the subject not obscured or confused by foreground elements and focus on it; then, holding the focus-lock button on the camera, lock that focus in place while you shoot. This technique works very well. If you don't know where the 'focus lock' button is on your camera, check the manual to find out. It's an important tool in focusing successful on your subjects.