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Wednesday, February 28, 2018

Canon 7D Mark II Autofocus Guide (Part II)

In the previous article, I mainly examined the use of the AF Configuration Tool, which is part of the menu system of the 7D II. These cases are a very important feature when using AI Servo. In this post, I will look at the remaining features of the 7D II's auto-focus and how they are best used for wildlife or general nature photography.

AF Area 

Canon now supports seven options for selecting various groupings of AF points.  Along with these new options, the 7D II has a new AF group selection lever.  This lever surrounds the joy stick on the back of the camera, but the lever has to be enabled as the group selection lever in the button settings. Below is a view of the new AF group selector switch.

To Configure the AF Group Lever to Scroll Through the AF Areas:
  1. Navigate on the Menu to Custom Function III - Display/Operation
  2. Enable Direct AF Area Selection

Single Point Spot

Single point spot has been around for several generations of camera bodies.  You can really think of it as a more precise version of single point.  In essence, it uses a very small point within the outer AF point rectangle.  This is useful for photographing a subject where getting a precise part of the image in focus is very difficult .  For example, if you were photographing a still bison portrait, you could use this feature to focus on the eye only and not have to worry so much about getting the eye lashes in focus.

In practice, I and most other wildlife or general nature photographers do not use this feature.  I am not saying it can't be used, but it has a very unique application and should not be used with AI Servo.

Single Point

Single point has been around since the invention of auto focus.  Essentially, you just move this point around the view finder, and place it over the area you want to be in focus and half press the shutter button to focus.  This is an important tool in my photography and accounts for probably 95% of my AF needs.  I use this when photographing landscapes, static subjects of any kind and macro.  However, most of the time I use manual focus when photographing static subjects and use live view to zoom in and focus for critical applications.

To use this feature, you must understand how to navigate the AF Rectangle around the view finder.  There are several ways to do this, but the best way to do it is as follows:
  1. Press the AF mode button on the top right of the camera body and immediately release it.  This puts you in a mode to actually select and AF point.
  2. While looking through the view finder, move the joy stick on the back of the camera, and watch the AF rectangle move from point to point.  
  3. Find the point which will allow the best focusing for your subject. For example, always focus on the eye when taking a portrait.
It is also important to note that this is the only way to use the center AF point when using an f8 lens.  It must be on the center point when using this feature. It is fine to use this mode in AI Servo continuous focus mode.

AF Point Expansion (4 Surrounding Points)

This AF group was part of the original 7D and one which I find useful from time to time.  I have used this successfully when photographing birds in flight, and it is one of my go to options to this day. It is good for slower moving birds and birds which are dipping into tree line. 

Essentially, when using this group, the center point is still the main AF point, but if the photographer gets sloppy or the subjects moves, the AF system will hand off to one of the surrounding points so the subject is kept in focus. Canon calls these extra points "assist points."  Note that as you move this focus point around, you can see the surrounding points move with it.  

AF Point Expansion (8 Surrounding Points)

This is the same type of AF group as the 4 point expansion.  The only real difference is that it contains 8 points to which it can hand off to when needed.  This was not included in the original 7D, but it is one in which I may test.  I could see using this mode when photographing birds against a blue sky for example.  I do not think this would be a particularly good mode for mammals in a wooded area however. 

Note: You may also have trouble with the AF locking onto other parts of the animal that you do not want in focus.  Canon literature does state that this mode resists grabbing the background inadvertently.

Zone AF

This is an AF feature which uses 15 AF points which can be moved to essentially 9 different locations on the view finder.  Zones are really best to use when you have a faster and more erratic subject.  Use this when you simply cannot hold the AF point on the subject.  At least it will lock on to part of the subject and with enough depth of field you will be in pretty good shape.

Large Zone AF

Large zone AF takes clusters of auto focus points and arranges them in three possible zones (left, center and right).  Using large zone, the camera will focus automatically on the closest subject in the zone.  This might be undesirable if you are in an area with many distracting objects in the foreground or at the same level as the subject.  This is also new with the 7D Mark II.  

All AF Points

In this mode, the subject is determined by the entire view finder.  Holding the shutter button half way down will cause AF to search for the subject and then the AF point will appear over the subject.  The problem with this mode is that you are leaving the subject finding and tracking to the camera body.  As you can guess this might, for example, track the foot of a bird and not his head.  This mode is best used when you have a solid background such as a blue sky and depth of field is not a real issue. 

I use this mode when I have a ridiculously erratic subject such as a swallow or a chimney swift.

Which Mode is Best for You?
Without a doubt, I recommend starting with "single point" and mastering its use.  For most subjects this is going to work fine.  Only use the more advanced zone features when you have no other alternative or you have a very shaky hand when shooting flight shots or rapidly moving mammals.  If you are photographing very erratic subjects and you simply cannot get them in focus, try one of the group modes.

I hope you enjoyed this third posting on the Canon EOS 7D Mark II!

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