The most important task is to choose the correct area mode to focus your subject. Based on your correct decision you get a better result. I always mention in my blog that thinks before you press your shutter button. Because you must know your subject, your autofocus setting etcSuppose you choose more focusing points like D9, D21, and D51 so it's better to cover the larger area, moving subject, sports, vehicles etc. Autofocus area mode comes in a picture when you tell your camera to use all those focusing points for better stunning images. However, the important thing is that your autofocus system is made up of focusing points, which correspond to regions that your camera can focus on.
Area modes are having few better options to focus your subject. I suggest choosing all the options one by one to see the difference in the results. This will educate you in a better way.
Single-point AF Area mode: When you are shooting a stationary subject or non-moving subject. Not good for tracking the subject can be little good with continuos subject but not for tracking subject.
Dynamic-point AF Area mode: Your camera focuses on the subject when it is moving, the camera track your subject into some of the surrounding points and shoot.
3D Tracking AF Area-mode: Your camera follows the subject when moves up and down and right to left or left to right across the focusing point. But sometimes it is not accurate, because you are not able to pan your camera, and can't take a close shot of your moving subject in this case you choose the 3d tracking option. Choose dynamic AF area mode in this case and I assure you you will find this more accurate.
Group area AF - The camera auto focus on the group of people, birds, animals etc and give equivalent focusing weightage to shoot. It can focus on the nearest point to focus the group. Try and see the result
Auto Area AF - When your camera scan and decides the closest subject to shoot. Like, can choose your subject face, the nearest tree, and any interesting point as per the camera. But It gives less control to the photographer to shoot. The choice is yours.
Now all the DSLR cameras are having all these AF area mode options. Its works better in video making. Must try to shoot on all those modes as discussed and see the difference in your results,
Keep experimenting and Have wonderful and happy photography life to you all
Photographer & Blogger Prasenjeet Gautam (www.prasenjeetgautam.com). has captured the above-posted photographs, Butterfly. INDIA. Other Diagram Image courtasy - Google