Autofocus Modes on canon Eos 7d

Choose the correct Autofocus modes it’s very important when you gonna shoot some photos. The more familiar you are with its capabilities, the better your ability to apply them to your needs. This quick guide attempts to explain you the special features of Canon EOS 7D which provides a versatile 19-point autofocus system, five AF-point selection modes, and three AF shooting modes.

AF SHOOTING MODE OPTIONS

One Shot AF
In this mode the AF system is set to focus on a stationary object. Once the system has confirmed sharp focus, a half-press on the shutter button will lock focus. You can then re-compose (if you wish) before you release the shutter.
AI Servo AF
In this mode the AF system is set to detect a moving subject, focus on it, and maintain focus as you release the shutter.
AI Focus AF
The AF system will automatically choose between One Shot AF or AI Servo AF based on whether it perceives the subject to be still or in motion. Keep in mind, however, that because AI Focus may not always be able to discriminate between subject and camera motion.

AF POINT SELECTION OPTIONS

Automatic AF Point Selection 
When you select this mode all 19 AF points are active. You’ll see a thin border around the entire AF point area, which indicates that Automatic AF point selection is active. The 7D will focus on the closest subject. The point(s) being used will appear on-screen.

Zone AF Point Selection
Zone AF works the same way as Automatic AF point selection except that it restricts the AF points to a small zone you have pre-selected. Within this zone the system will focus on the closest subject. You can select from one of five zones:

• Nine-point cluster in the center
• Four-point triangular cluster to the left
• Four-point triangular cluster to the right
• Above the center
• Below the center

Manual AF Point
Manual AF point selection allows you to pick any one of the 19 AF points to be active, with the rest inactive. A single AF point, visible in black (or illuminated red) clearly indicates where the camera is looking to focus.

AF Point Expansion
AF Point Expansion allows you to manually select one AF point to be the primary point you want to use. As long as there is adequate detail, the system will concentrate focus on the one point you have selected.
If for any reason the system point loses sight of the subject or can’t find sufficient detail, it will automatically activative the surrounding AF points. The number and location of surrounding AF points will vary depending upon which AF point you manually selected. There is no way to add or subtract the surrounding AF points.The viewfinder will, however, display the expanded points.

Spot AF Point
The difference with Manual AF Point Selection is that the AF point is smaller and more concentrated. This allows you to read an even smaller area of the subject and focus even more precisely on one particular element in a scene. When Spot AF is active, a small secondary box appears inside of your manually-selected AF point. You will see a “box within a box” in the viewfinder.

That’s all about Autofocus Modes. See you guys