School me on my 70D's AF Drive and Selection please!

I was out shooting with my new (refurbished) 70D this weekend at my kid's soccer game. I absolutely love the camera (at least compared to my T2i).

Question about AF Drive and Selection. I had my camera set to AI Servo and single point AF selection (used center point). I've read through the manual (both short and long) but still have a question about the two.

One option for the AF is the 19-point with "tracking." According to the manual (although I haven't tried it) - you can select 19-point focusing and also select the individual focus point you want the camera to "start" with when focusing.

Is this a better option to use for sports shooting that the method I used? If I am burst shooting - and the kids are moving around - it seems like I would lose focus if the left the center AF point. Should I be using 19-point / tracking - and selecting the center point to start focus?

Everything I've read suggests to get off the 19-point and use single point.

Any thoughts?

Google MichaeltheMentor 70d focus tutorial, it's a video on YouTube.

510storm wrote in post #17142716
Google MichaeltheMentor 70d focus tutorial, it's a video on YouTube.

Yes! I watched that video and decided to post my original post. Michael says to dump the 19-point autofocus and select a single point. My question is - if I do that - have I eliminated the 70D's ability to "track" a subject if it leaves the selected AF point?

If no - what is the difference between 19-point AF with tracking and Single Point AF selection in AI Servo?

It depends on the circumstances.
If you are tracking with one point only, you have to keep that on the subject all the time, or at least most of the time. The tracking sensitivity parameter will define the timeout before the camera considers the subject lost and tries to refocus on something else.

If you instead use expansion points, i.e. points surrounding the selected one to aid as auxiliary tracking points if the main one looses the subject out of sight, then you give the camera the option to hand over to another point instead of just loosing track and refocusing. But that also implies that the risk that the camera will change point by mistake increases, especially if you have many expansion points active at the same time. Using all 19 points only works well when the background is reasonably calm. Using only four expansion points is a better compromise between coverage and risk for selecting the wrong point, but since you have a 70D, that's not an option for you. It takes at least a 7D to get such a mode.

You simply have to try what works best for you. Zone AF also gives less points, but still more than one, but sometimes the fact that zone AF makes its own decision about with which point to start is a drawback.

I tend to use the AI Servo with zone AF (the center zone), and move my camera with the action. This seems to give me a good keeper rate when shooting JH sports- as long as I start it on the right subject. As Anders mentioned though, if it locks on the wrong thing, you might have to reacquire AF to get it to track your subject.

stop using 19 automatic AF selection, pick your composition and choose your single point accordingly while using AI servo.

For more distant shots, which is difficult to track with single point, use AF zone mode. There are other options like tracking sensitivity, which works most of time well with default settings, but sometimes, it needs to be set differently to achieve perfect focus.

palad1n wrote in post #17143745
stop using 19 automatic AF selection, pick your composition and choose your single point accordingly while using AI servo.

For more distant shots, which is difficult to track with single point, use AF zone mode. There are other options like tracking sensitivity, which works most of time well with default settings, but sometimes, it needs to be set differently to achieve perfect focus.

They aren't using 19 pt, they are using center, this post is asking about what other options could be used. This is called out in the op.

OP asked about this : "One option for the AF is the 19-point with "tracking." According to the manual (although I haven't tried it) - you can select 19-point focusing and also select the individual focus point you want the camera to "start" with when focusing."


i just used bad words ... instead of "stop using" i should probably say "don´t use"
Sorry.

I'm hardly an expert but I've had better success with birds in flight using the center point only with AI servo. I tried center zone and it seemed to switch the AF to things other than the bird too much for my liking.

I suspect that is why so many wildlife photographers with limited budgets love the 7D so much: the expanded center point.

My experience says that the larger the number of expansion points is, the larger is also the probability that the camera will pick the wrong one when it looses track with the primary point.

After all, that's rather reasonable.
However, I've also found that at least if there's a specific color on the main target, then the 1DX is very capable in tracking that particular color, provided the iTR function is enabled. Like in this picture, where the shirt really has its own color.

To clear up some confusion about all points/19 point auto focus -

If you are in One shot, it'll act like auto mode and select whatever's nearest.
If you are in AI Servo, it'll show you a single point as active then use the rest of the points to help track the subject. It's like single point AF but with 18 extra helpers for tracking.

78962 wrote in post #17143984
To clear up some confusion about all points/19 point auto focus -

If you are in One shot, it'll act like auto mode and select whatever's nearest.
If you are in AI Servo, it'll show you a single point as active then use the rest of the points to help track the subject. It's like single point AF but with 18 extra helpers for tracking.

First - I very much appreciate all the help folks have to offer on this forum. It's been a great resource for me. With that . . . .

So, if I am in AI Servo - I have the following options:

1. Use single point AF - but I need to keep the subject within that single AF point.
   
2. Use Zone AF (likely using the center Zone) and select the center AF point as a "Start point" for the 70D's focus system - and the 70D should track the subject so long as it's in the center zone.
   
3. Use 19-point AF with tracking, use the center AF to start - and the 70D should track the subject anywhere in the AF area.
   

That seems to be my experience with the 70D tracking.
Center zone gives me the best of everything, as I can track the target and have some room for movement.
Single point didnt work for me, but Im guessing adjusting the tracking settings could have helped in keeping the target in focus after it left the zone.
And 19 pt wasnt that useful, as the camera would sometimes pick targets outside of the subject.

If anything, go to a local game and play with the camera. I toyed with it on softball games and it worked pretty good. Lots of keepers.

When using zone AF, you can't decide which point to start with. The camera will start with one it finds appropriate, then use that as the main point and the others as helper points.

You don't have to start with the center point when using all 19. If composition says that you want to focus on something a bit to the right, perhaps because it's moving to the left and you want it to move into the image, then select a starting point to the right.

It's only the 1DX which can use color informaton for tracking. Your camera will only use the helper points if the main one looses track for longer time than the timeout you've set, and if that happens only focus information will be used to try to figure out which point is most appropriate to hand over to.

apersson850 wrote in post #17144325
When using zone AF, you can't decide which point to start with. The camera will start with one it finds appropriate, then use that as the main point and the others as helper points.

You don't have to start with the center point when using all 19. If composition says that you want to focus on something a bit to the right, perhaps because it's moving to the left and you want it to move into the image, then select a starting point to the right.

It's only the 1DX which can use color informaton for tracking. Your camera will only use the helper points if the main one looses track for longer time than the timeout you've set, and if that happens only focus information will be used to try to figure out which point is most appropriate to hand over to.

Anders - thanks for your reply. Here's a page from the 70D manual - discussing selection of the initial AF point in 19-point AF mode with AI Servo selected. Am I misinterpreting the manual?