Canon 7D2 auto focus quesrion

[Stillh2o]

While in servo mode, under what setting can I use a single focus point to track a subject?

[diverhank]

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@Stillh2o wrote:

Just to make sure I am understanding what you are saying, if I am in single point AF in Servo, the single point will not expand to 3 or 4 points together and track the subject I am foucused on?

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Correct.  It will longitudinally (moving away or towards you) but if it moves laterally it won't with a single AF point.  You need to choose a mode that has multiple points and it will auto select the point for you as the object moves laterally.  Usually the most effective is the center point with 8 assists.  I use it 95% of the time for BIF.

Here is a really good Canon guide for the 7DII...you should read it.

http://learn.usa.canon.com/resources/articles/2014/eos7dmk2_afGuidebook.shtml

[Stillh2o]

Okay, it is one of 2 things.  1. I did/am not using the corrects terminology, words or not explaining what I mean well enough or 2. you are incorrect.  I can use the single AF point and it will expand but you have to go into the menu and change a setting.  

[TTMartin]

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@Stillh2o wrote:

Okay, it is one of 2 things.  1. I did/am not using the corrects terminology, words or not explaining what I mean well enough or 2. you are incorrect.  I can use the single AF point and it will expand but you have to go into the menu and change a setting.  

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You are referring to AF point expansion mode, which doesn't behave like you think it does. With AF point expansion mode (4 or 8 point) the center AF point will attempt to focus on the subject, if it fails to detect a subject only then will it use one of the surrounding AF points. It does not track and hand off to the adjacent AF points like when using auto AF point selection and AIServo. 

[diverhank]

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@Stillh2o wrote:

Okay, it is one of 2 things.  1. I did/am not using the corrects terminology, words or not explaining what I mean well enough or 2. you are incorrect.  I can use the single AF point and it will expand but you have to go into the menu and change a setting.  

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Most likely you are using the wrong terminology. No matter, you figured out what you need.  Most likely you are looking at the square that is the initial AF point in one of the expanded focus group.  When you say "a single AF point", it's just one single point.  You use this mostly when you want precise focus on the eye.  

The link I provided will help you with the correct terminology.  It's possible that I'm wrong but I don't think so.  I'm done with this topic.  I'd like to help those who want help.  I don't think you're interested in it.

[TTMartin]

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@Stillh2o wrote:

Just to make sure I am understanding what you are saying, if I am in single point AF in Servo, the single point will not expand to 3 or 4 points together and track the subject I am foucused on?

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What you want is to be in an auto AF point selection mode.

All Canon dSLRs behave differently when it comes to auto AF point selection mode and AIServo compared to One Shot focus mode.

When in an auto AF point selection mode and One Shot the camera will choose from all available AF points and choose the closest active AF point that has adequate contrast to achieve focus.

When in an auto AF point selection mode and AIServo, the camera starts with a single AF point and uses the other active AF points to continue to track the subject if they move away from the starting AF point.

For most Canon dSLR the starting point for tracking when in auto AF point selection mode and AIServo is the center AF point. Starting with the classic 7D more advanced cameras allow you to choose a different starting point for focus tracking when in auto AF point selection mode and AIServo. Just to confuse things the 7D Mk II also allows you to set it up, so it will automatically choose the starting AF point, much like other cameras do in auto AF point selection mode and One Shot. This however is not the default way the camera is set up, and you would need to reconfigure it to do that.

So what you actually want to use is either the 65 point auto AF point selection and AIServo, or one of the Zone auto AF point selection modes and AIServo. This will start with a single AF point, and if your subject moves off that AF point laterally the camera will hand off focus to one of the adjacent active AF points and continue tracking your subject. 

[TCampbell]

Make sure you download and read the guide that TTMartin linked above. 

The 7D2 is what I refer to as a "technical" camera.  It's capabilities are more advanced than a typical DSLR, but it does require taking some time to read through it's capabilities and how to use them.

There are a number of configurable options that control how the camera can "follow" a moving subject as it moves through the frame.  

Normally you do that by allowing it to use all the AF points (set it to use the full AF area... not a single point), BUT... you set the initial point and the focus system will attempt to "track" your moving subject.  In other words it doesn't really use all the points at the same time... you give it permission to switch to adjacent points as needed to follow your subject movement.  It really just focuses to the one point -- but using the full AF area gives the camera permission to switch points as your subject moves.  If you pick a "single" AF point then you've locked it only that point and it is not allow to transition to adjacent points as your subject moves.

Also... how it tracks subject movement is configurable.  If something should momentarily block the view of your original focus target do you want the camera to ignore it and keep the focus distance maintained (hoping the object blocking your view will soon be out of the way) or do you want it to switch focus to the new subject?  There's no "right" answer for every situation, so Canon set up the focus system so that you can configure it's behavior.  That way you can configure the behavior that works best for your current situation.

[Stillh2o]

My question was where to go to activate what I wanted it too do, not how to use the AF.  I found where I needed to go in the settings to accomplish that.  

[Stillh2o]

Okay. I appreciate everyone's input. Like I stated earlier, I found where I needed to go to in the menu to accomplish what I was needing.

[Stillh2o]

Okay, like I have said before I have a single AF square. When it locks in on a subject, other focus points surrounding it will come up. It is a single point, not expanded.

[Stillh2o]

Okay, thanks.