Zone AF:

This is totally new, never possible with any previous EOS digital SLR. It’s bound to be a popular option for different types of shooting, particularly for photographers who are shooting quickly, and for moving subjects where you need a broad area of focus coverage. Most importantly, it lets the camera focus upon whatever is nearest within that area, whether you're in One-Shot AF or shooting a moving subject in AI Servo AF.

In effect, Zone AF is Automatic AF point selection, but restricted to a small cluster of AF points in the viewfinder.

To activate Zone AF, either press the rear AF point select button and then press the M.Fn button until a cluster of AF points appear in the viewfinder with curved brackets surrounding them, or alternatively press the “Q” button to call-up the Quick Control menu, and use its AF area mode option to toggle through the choices until you see two smaller brackets, and “Manual select.: Zone AF” spelled-out at the bottom of the rear LCD monitor.

Zone AF has the potential to be especially useful for action photographers, shooting subjects ranging from track and field to birds in flight. Again, it’s particularly adept at picking one nearest subject from a range of subjects, like a cluster of runners at a track meet, and putting sharpest focus on that which is nearest.

Five different zones are available: dead-center, upper- or lower-center, and left or right. As with AF point expansion, there’s no way to increase or decrease the size of a zone. You can only move it as just described. It’s also not possible to “nudge” it just a little to the left or right, for instance; only the five pre-set locations are possible. Even with these limits, this is a spectacular new option for EOS users, and a very interesting way to harness the power of Automatic AF point selection with some of the control users have previously had with Manual AF point selection.

Finally, an important distinction between Zone AF, and the previously-mentioned AF Expansion settings:

AF Expansion lets the user pick ANY of the 19 AF points, and the camera then uses exclusively that single AF point for focus — unless that point cannot see the subject, or unless the subject moves away from that point. In either instance, the surrounding, expanded AF points are now used to attempt to continue to focus upon the subject.

Zone AF lets the user pick a ZONE of 9 AF points (center zone only) or 4 AF points (any of the surrounding available zones). Automatic AF point selection occurs within this zone, with the camera using whichever AF point sees the nearest subject with detail in that zone. The photographer can pick a zone, but cannot pick one point within that zone to be a primary point, as he or she could with AF Point Expansion.

As mentioned, Zone AF can be very helpful when you know you want the nearest subject among two or more to be the one focused upon. It is less useful when you want to focus precisely on one part of a subject — for instance, in a head-and-shoulders portrait, Zone AF might put the tack-sharp plane of focus on a subject’s nose, instead of his or her eye, if the camera “thinks” the nose is nearer to the photographer.

For a more in depth information on the EOS 7D Auto Focus System, please click on the following link:

http://www.learn.usa.canon.com/resources/articles/2011/whats_news_eos7d_article.shtml