Certain images are just easier for your camera to get in focus than others. In wildlife photography acquiring focus is not nearly as important as the camera's ability to track the focus (keeping your moving subject in focus). Once again, this can be a lot more difficult for certain situations than others. When animals have a clear blurred background your camera will smile. When animals move in behind other objects that obscure the camera's view of the animal your camera will cry. When the animal blends in with its surroundings and has similar looking or colored things very close to it, between it and the camera and right behind it in the background, your camera may throw a tantrum. The poor camera and lens will have to hunt for focus. It racks the focus forward and backward and most of the time everything looks out of focus, all the while, while your animal walks away. This is so frustrating both for you and your camera. Here is an image of just such a situation.

How can we make life easier for ourselves and our cameras in situations like this? The setup of your autofocus system has a lot to do with your success. Your camera (if "pro" enough) will have different autofocus settings. For great wildlife photography set the stickiness of the autofocus system fairly high. This way branches or grass will not let your camera lose focus.

          Secondly, when it is difficult to spot your subject, I prefer to take the camera out of the zone focus mode and I pick a specific focus spot. This tells your camera what you want in focus. You just hold the focus spot right on your target and then focus. Once focused your camera can lock onto your animal and the stickiness of the system will prevent it from being distracted by other things.

          Know the different focus settings of your camera and set it up for each situation. This is easier said than done. Cameras are computers that happen to be able to take images. They have hundreds of different settings and combinations of settings and menu choices. How are we supposed to remember the right settings for each scene, let alone how to actually set it that way and where to find the right settings in the menus?

          May I suggest a few helpful tips?

• Use the "my menu" option in your menu settings. Store the most used settings there so that you don't have to search for items in the menus. Animals tend to move, they don't wait for you to change your camera's focus settings. Getting to the right settings instantly speeds things up dramatically.
• An even better option is to set up and use the custom setting located on your mode dial. My camera has three custom settings there. I have one option programmed for landscape photography, another for wildlife (slower moving), and another for fast action. Once set up correctly, one turn of the dial has my camera set up perfectly for the situation at hand, and I don't have to remember or fiddle with any menu settings.
• A third option is to use a custom button anywhere on your camera. My normal back focus button is set up one way while another button is set up for another focus mode. Focusing becomes really simple, press this button for zone focus and that for spot focus, for example.
• If you don't shoot regularly, make sure you know which button or dial function does what before you go out photographing.

Having said all of that please know that not all autofocus systems are created equally. Some manufacturers shine at autofocus while others are slower and less sticky. Within each brand each tier of camera (consumer, prosumer, pro) will have different autofocus capabilities. Choose the right camera for what you want to shoot.

          All the best.