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Tuesday, February 13, 2018

Canon 7D Mark II Autofocus Guide (Part I)

There is no doubt, that the Canon 7D Mark II's auto-focus system is a huge leap from the previous Canon 7D.  In this article, I will attempt to unravel the complexity of this system by gathering expert sources as well as my own experiences with the new system.  Particularly, part 1 will look at the basic configuration of the AF points and the AF cases.  This, of course, will be written from a nature photographers perspective.  

65 AF Points
The most obvious improvement I first noticed is the expansion from 19 AF points in the Canon 7D to 65 in the Mark II.  As shown in the image below, this gives the photographer almost edge to edge AF point coverage.  All 65 of these images are cross type on lenses which have an aperture of 5.6.  What this amounts to is the camera uses both vertical and horizontal planes to find focus on the subject.

Of course having 65 AF points, all cross type is a welcome addition, but what does this mean in practicality?  If the photographer is using one of the popular Sigma and Tamron 150-600mm lenses, they cannot reliably use cross type auto focus above 400mm.  At that point, the lens becomes a 6.3 lens and not a 5.6 lens.  So for wildlife photographers on a budget, cross type points may not be that big of a gain. If, however, the photographer is using lenses such as the Canon EF 100-400 II or the Canon EF 400mm 5.6, they can take full advantage of the entire grid of AF points in regard to cross point functionality.

Center Point AF
The center AF point, as with most professional bodies, has two additional properties which make it very useful for the wildlife photographer.  First, if the photographer is shooting at f8, the camera still maintains AF when using the center point.  Secondly, if the user is using a 2.8 lens, then he can benefit from the high precision diagonal cross type.  For most wildlife photographers reading this article, the high precision point, will not be an important feature as most do not own longer 2.8 lenses, but having a camera that can still reliably auto-focus at f8 is a huge advantage.  With this feature, one can use a teleconverter on his 400mm 5.6 lens and effectively be able to shoot at f8, 560mm.

The AF Configuration Tool
With the 7D Mark II, Canon has introduced a new configuration tool in the menu.  This tool allows the photographer to move through six different "cases" to better tailor the camera to handle certain auto-focus conditions.  Please note, that these cases only apply to AF when you have the camera set to AI Servo.  In other words this is for action shooting only.  Below each case will be examined and explained.

Case 1: Versatile multi purpose setting
As I expected, this case is best used when I have no idea what conditions I will be shooting in.  In essence, it is a general setting from which to start.  This is the setting I am currently using for all my songbird setup photography.  It is fast enough to handle a bird jumping from perch to perch as well as basic flight such as a slower moving great egret.

In this case, the tracking sensitivity, acceleration/deceleration tracking and AF pt auto switching are all set to 0 by default.  This provides a balanced approach to shooting moving subjects.  My personal feeling is to start here first and only change cases when the subject you are shooting demands the change.

Case 2: Continue to track subjects, ignoring possible obstacles
Use this case when you are shooting wildlife in and around other obstacles.  This is often a problem when photographing birds in flight that dip down through trees or bushes.  Because the tracking sensitivity, accel./decel tracking and AF pt auto switching are all set to a lower value, your auto-focus will not change focus as quickly to other obstacles in front of or behind your subject.

But, it is not just birds in flight that cause this type of scenario in wildlife photography.  Even photographing elk or backyard birds, sometimes it is best to not have the AF too jumpy and moving from subject to subject in the scene.  Sometimes we lose focus for a second and we don't want the AF to grab the background or some tree.  Case 2 is something I am currently experimenting with in my photography.

Case 3: Instantly focus on subjects suddenly entering AF points
This is almost the opposite of case 2.  In this case, we want the AF to jump to the subject as it enters the view finder.  

To me, this case, is a bit too jittery for most uses.  I know that there are situations out there where this might be the best solution, but I will most likely stay clear of this case for the most part.  Primarily in wildlife photography, we are trying to track the subject throughout its entire movement and not changing focus from one subject to another.  This case has souped up tracking sensitivity to force the AF to move to the new subject when  it is encountered.

Case 4: For subjects that accelerate or decelerate quickly
This case might become useful in scenarios where you are tracking raptors as they turn quickly and dive for example. I could also see this being useful when tracking a predator running after its prey.  I have not used this setting in the real world yet, so more to come on that in the future.

Case 5: For erratic subjects moving quickly in any direction
This case differs from the others in that it was specifically designed by Canon to work with AF focus modes such as center point expand and zone.  It increased the AF point switching so even if I were to move my tracking point off from the subject, the AF system will hand off to another point within the zone.  Although I have not used this case, I could see this being something which might be effective for older or beginning photographers who might find it very difficult to hold the AF point on the subject.  

One concern I have with this mode, is the potential to switch points of from the subject.  I may try to work with this case a later point in time, so stay tuned.

Case 6: For subjects that change speed and move erratically
Here, we have a balanced approach to extremely erratic subjects.  To me this would have to be a very unusual type of subject.  Canon uses the example of photographing a Kayak moving through the rapids.  It is changing direction and speed constantly so this option was recommended.  

In the wildlife world, the only scenario I can really think of is a case where a predator is chasing its prey around in circles and has sudden shifts in direction and speed.  Although this mode might be best in this scenario, I don't think I would have time to switch to this mode in time to photograph the action.  I think this one has better application in the sports world.

What other Professional Photographers are Saying about AF Tracking
As is state earlier, I wanted to gather more information than just my own experiences or what the Canon documentation specifies.

Martin Bailey - Martin is a professional nature photographer based out of Japan and I respect his opinion as being his own and not that of Canon or some other sponsor.  Martin, in the end, did not use any of the cases but rather changed the tracking, accel/decel and AF pt auto switching manually. He ended up using the setting he used on his 1DX for best results.  Here are his settings below:
"For both the snow monkeys running towards me, and birds in flight, both subjects moving erratically, I found these settings to work the best. I have Tracking sensitivity set to -2, Accel./decel. tracking set to 1 and for AF pt auto switching I’ve been moving between 0 and 1 depending on the subject, depending on how accurately it’s working in a given situation.With erratically moving subjects it’s important for the AF points to switch around quickly, so it’s tempting to increase the AF pt auto switching sensitivity, but as you increase the sensitivity, the focus often switches to an unwanted part of the scene too readily, so I found myself with AF pt auto switching set to zero most of the time." - Martin Bailey
Art Morris - Art, who up until recently was a Canon explorer of light, worked with the 7D II for several months and this is the setting he like best for birds in flight:

  • Tracking sensitivity: -2
  • Acceleration/Deceleration tracking: +2
  • AF pt auto switching: +2
This looks like a much more radical approach to AF, but you can't argue with Art's success. My recommendation is try it and see what you think.

Grant Atkinson - Grant is a Canon Explorer of Light and instead of using the default cases, he creates his own menu for the settings and essentially creates his own cases. Below are his settings:
  • Tracking sensitivity:  Grant doesn't have one setting for all scenarios, but he adjusts it as the conditions warrant it.  For example, if he notices that his lens is grabbing the background, he will turn his sensitivity down.  I got the feeling, although he did not state this, that he starts out at 0. He did say that in his opinion this was the most important setting in the cases.
  • Acceleration/Deceleration tracking: Leaves it a 0 for subjects that are moving at a standard speed.  Turns it up for erratic animals.
  • AF pt auto-switching - I got the feeling from his thoughts on this that he didn't use this too much.
Grant was definitely not someone who seemed to not have a "set it and forget it" attitude when it comes to auto focus settings.  I did find his videos informative, but I thought that he was largely just regurgitating Canon's literature.  

I thought that these three photographers give us a good cross section of what the pros are doing out there when it comes to the AF cases.

I hope you enjoyed this article on the Canon EOS 7D Mark II's AF.  In part 2, I will examine the various AF modes and when to use them.


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