5DmkIII - Do I have an AF tracking issue?

Hi all,
Have I an issue with my mkIII or am I doing something wrong?
Perhaps they're a little slow shutter speed wise, but are indicative of what I get when trying to track subjects. I shot a sequence the other day at 1/400 which would have been better to show you but the focus issue was the same( I was deflated and deleted them). Lucky to get one image sharp.

Is it usual for the focus points to move around so much? Some of the shots the focus points actually jump away from my boy.

I am doing something wrong here. Starting to became a little disheartened.

These are 50% views.

Specs of the images:
5DmkIII
70-200 f/4.0L IS USM
1/160,
f/4.0
Case 4
61 pt AF cross type only.

If you have all AF points set to track then i believe the camera will change AF points to follow the subject. I think the idea is you set the initial AF point and then the camera tracks the subject across the frame using the other points. You just need to make sure the subject covers at least one point. Ive never used it like this so i may be wrong (or simplifying it too much).
You can fine tunes these settings if you find they dont work well enough.
The last shot looks like motion blur to me.

You indicated "case 4", so I'm guessing you are familiar with the settings that it provides. I'm wondering, however, if you perhaps modified some of the parameters, such as tracking sensitivity, AF point switching, etc. Alternatively, you may want to boost those settings to get better tracking.

Also, check the AI Servo 1st & 2nd image priority settings. If you left them both at 'equal' priority for focus and release, that could be some of the difficulty as well.

I've tried different cases, different AF point selection modes and I can't seem to get sharp images shooting a sequence.
Yes AI Servo and both selections are set to focus priority and yet when there's clearly nothing in focus it still takes a picture.

Ive just noticed the slow shutter speeds. This could well be the problem.
The top right image has the boys face blurred but the ribbing on his collar is in focus, so id say focus was achieved but his head is moving too fast. Same for the bottom left shot although to me that looks fine.
I'd say you just need to practice a bit more. We've all read how much better the AI Servo is on this camera, but i feel it still takes a bit of practice, and with the correct settings for the job, before it becomes more consistent. Or maybe thats just me.

swoffa wrote in post #15639275
I've tried different cases, different AF point selection modes and I can't seem to get sharp images shooting a sequence.
Yes AI Servo and both selections are set to focus priority and yet when there's clearly nothing in focus it still takes a picture.

The 5D3 will take an OOF picture unlike the 5Dc which requires focus lock. I can't remember if that's a default setting on the 5D3 or if it's something you set, so that makes sense it will still take a picture.

With that much (fast) movement, I'm wondering if you inadvertently left the AF setting at Single Shot AF. That would easily explain the missed tracking...as in...been there and done that myself!

1/160 is not fast enough to get a clear picture with a subject moving. I doubt it is the camera and more likely operator error.

bsmotril wrote in post #15639418
1/160 is not fast enough to get a clear picture with a subject moving. I doubt it is the camera and more likely operator error.

I'm always amazed how fast kids move . I found that out painfully with medium format film over a the years.

sapearl wrote in post #15639302
The 5D3 will take an OOF picture unlike the 5Dc which requires focus lock. I can't remember if that's a default setting on the 5D3 or if it's something you set, so that makes sense it will still take a picture.

By default, it is set half way between release and focus. If it's set all the way to the left (release) it will try release the shutter over achieving focus lock. It's the 2nd menu option under AF called 1st priority or something like that if the OP wants to check.

OP, why are you using case #4? Something like you are shooting above should be case #1 or #2.

Also, the OP said they were using 1/400th of a second with the same results.

Gregg.Siam wrote in post #15639575
k.

OP, why are you using case #4? Something like you are shooting above should be case #1 or #2.

How can you tell? Why "should" the other cases be used over 4?
Case 4 seems like the correct one to use to me. For situations where the subject accelerates and decelerates quickly, like soccer/basket ball etc. If the boy is running around i cant see why this wouldn't be used (but im open to be told otherwise)

Just asking.

Redo your test with a SS of 1/1000 to completely eliminate motion blur as a variable.

You definitely have a lot of motion blur in these images and that makes it harder to discern if you have a tracking issue or not.

The focus points moving around a lot is tracking sensitivity. I use Case 2 when I'm shooting birds perched so that the focus points don't jump around as much. This should apply to your situation. The SS is also way too slow. It should be at least 1/500 or faster. On a sunny day, I set the ISO to 160 and let the SS go as high as it wants. I'm usually in Av mode and will set the f-stop at f5.6 or f6.3. I also set the AF area to single point expansion which should work for your situation. I'm only assuming you use back button focus to shoot in AI Servo. I have had better success with 1st and 2nd image priority set to focus for both. With the 1D X and the 5d III, I don't set the VF to see only cross-type focus points. I'm very confident with all the accuracy of all the focus points in both the 1D X and the 5d III. Hope this helps.

1. Pick one point and sorrounding points if you want. For best case start with center AF point. No 61 points stuff.
2. High enough ss like 1/1000 or better like 1/2000.
3. AI servo, case 1
4. Change priority of 1st and 2nd image to focus

Now run the test making sure you tracking with AF points on him all the time.

Thanks everyone for your feedback.
I do have 1st & 2nd image priority set to focus. I've tried in just about all cases and I may get one sharp image out of sequence of a dozen. Yes definitely AI Servo, I rarely use one shot as my boys are only still if they are playing computer games.

I will redo this with a much faster shutter speed today and post back some results.