Canon 7D: Zone Auto Focus, The Good, The Bad And The Ugly

category: Cameras • 2 min read

Please note that there is no ugly part. I just liked how the title sounded by adding the word ugly. I am too weak to resist the opportunity to do a bad pun.

The auto-focus is the most complex problem in a modern camera. It has to be right, accurate, repeatable and all this in real-time. Canon needed a solid reply to Nikon’s CAM3500, the AF module introduced with the Nikon D300 and the Nikon D3 family. So Canon’s reply is to provide 6 different ways of using the auto-focus system? Each focus mode has it’s strength, it’s weakness and pitfalls. It’s not that simple.

Let’s look at the Zone Auto Focus. The focus system is made of 19 points. The 19 points are divided in 5 zones. The Digic-4 processor will process only the points in the selected zone:

  1. Centre: 9 points
  2. Left: 4 points
  3. Right: 4 points
  4. Upper: 4 points
  5. Lower: 4 points

Canon 7D -- Zone Focus

Canon 7D — Zone Focus

Please note that the following image is borrowed from Canon. You select the zone with the joystick. Once you have selected the zone, Canon will focus on the nearest contrasted object/subject.

The good of the Zone Auto Focus

  1. Because of having a fast CPU dedicated to the auto-focus and the simplification of having less auto focus points to process, it’s fast, it’s so fast that to me it looks like magic.
  2. It’s great for AI Servo Auto Focus, such as birds in flight, car races…
  3. It’s outstanding when the object/subject comes toward you.
  4. It’s great for focusing on far away objects/subjects.
  5. It’s great when the thickness of the object/subject is less than the depth of field. This will depend on the object/subject, the distance, the lens and the aperture of the lens.
  6. It’s great when you want to focus on the front of the object/subject.
  7. It’s great because you do not have to choose which point to focus on. The 7D will do the selection of the focus point for you. Selecting the zone is much faster than selecting the focus point.

The bad of the Zone Auto Focus

  1. The Zone Auto Focus will focus on the nearest contrasty object/subject within the zone.
  2. You do not get to choose which point to focus on. The 7D will do the selection of the focus point for you.
  3. It will not work if you want to focus somewhere else that the front of the object/subject.
  4. The Zone Auto Focus is wrong for focusing on close or very close objects/subject where the depth of field is much more limited and you want to focus on something else than the front of the object/subject.
  • Please note that it’s not bad in itself, it’s a limitation of that specific implementation.
  • As long as you know how the Canon 7D behaves, you can select the correct mode for your situation.
  • You can always choose another focus mode.