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Frequent Contributor
Posts: 95
Registered: ‎01-30-2018

AF Accel./decel. tracking Question

1DXII, but I know these features are available on other models. 

 

I have a good handle on "tracking sensitivity" and "AF pt auto switching" as well as understanding how a [+1/+2] setting for "Accel/decel tracking" would make sense.  But I am having a tough time with the real-world use case for going to [-1/-2] for "Accel/decel tracking."  From the AF Manual: 

 

"A minus setting for subjects with a long shooting distance such as soccer provides more stable focus. ...  [-1/-2] are effective for shooting far away subjects with small changes in speed when you want to focus on minimizing the effects of obstructions passing by in the foreground of the shot." 

 

That last bit confuses me because that's also what the "Tracking sensitivity" option gives you.  Only thing I can think of is that when subject is far away (let's say Player A in soccer) and Player B runs right in front of them, the camera system may think that Player B is really just an acceleration of Player A toward the camera, and therefore try and adjust AF accordingly.  In other words, the only way the manual's instruction makes sense to me is if there is a scenario in which a player crossing in front of my AF Locked player gets misinterpreted as "acceleration."  And that this must only occur when subjects are far off, vs filling the frame where "Tracking sensitivity" would be the more obvious setting.  

 

Any thoughts as to whether that is correct?  Otherwise, I just can't see a good use for [-1/-2] for Accel/decl tracking.  

 

 

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Respected Contributor
Posts: 1,152
Registered: ‎01-25-2018

Re: AF Accel./decel. tracking Question

Coach,

 

I interpreted the AF guide the same way you did.

 

At a great distance a player cutting close to and in front of the player of interest is likely to be interpreted as acceleration of the subject causing loss of focus lock on the desired subject but depending upon distance and F stop this may not be much of a real issue depending upon DoF.  At this distance with the effective DoF it becomes more difficult for the AF system to distinguish between the subject moving towards the camera versus another player who is in very close proximity of the subject cutting in front but if you are shooting with a fast lens wide open (pretty typical sports shot) then this abrupt shift in focus with lock on the undesired subject will be a problem.  Although the tracking sensitivity algorithm is likely to provide false results in this situation programming a lag into the accel/decel tracking causes the system to effectively ignore this brief distraction.

 

The 1DX M2 AF system is definitely the best I have ever used and it is good that Canon brought out the additional manual for the AF system but it is still awkwardly worded in many cases making it somewhat difficult to determine exactly what the impact from a specific setting change will create for the system.

 

For some types of sporting events a single AF servo setup will pretty much do just about everything for you but soccer isn't one of those types of events.  There are so many different scenarios in this game which is played on a very large field that you basically need to choose the best set of AF servo parameters for the situation you expect (or plan to shoot) the most and then keep in mind the limitations of that parameter set for other situations and compensate by your input as the photographer helping the system to provide the desired results. 

 

In soccer situations when there is a lot of passing going on then fast lock on the new subject is more important than having the system ignore "interference".  Last Spring I was shooting mainly high school varsity soccer with a lot of long ball control runs by a single player but I also shot a few of the "puppies" games that the coach ran to teach pre-school kids the basics of soccer.  Getting photos of the young kids was almost like shooting a pro game because a LOT of passing was going on but in this case the "passes" were often to the opposing team and the best AF setup was to speed acquistion of the next desired subject.

 

Rodger

EOS 1DX M3, 1DX M2, 1DX, 5DS R, 1D M2, EOS 650 (film), many lenses, XF400 video
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Frequent Contributor
Posts: 95
Registered: ‎01-30-2018

Re: AF Accel./decel. tracking Question


@wq9nsc wrote:

Coach,

 

I interpreted the AF guide the same way you did.

 

At a great distance a player cutting close to and in front of the player of interest is likely to be interpreted as acceleration of the subject causing loss of focus lock on the desired subject but depending upon distance and F stop this may not be much of a real issue depending upon DoF.  At this distance with the effective DoF it becomes more difficult for the AF system to distinguish between the subject moving towards the camera versus another player who is in very close proximity of the subject cutting in front but if you are shooting with a fast lens wide open (pretty typical sports shot) then this abrupt shift in focus with lock on the undesired subject will be a problem.  Although the tracking sensitivity algorithm is likely to provide false results in this situation programming a lag into the accel/decel tracking causes the system to effectively ignore this brief distraction.

 

The 1DX M2 AF system is definitely the best I have ever used and it is good that Canon brought out the additional manual for the AF system but it is still awkwardly worded in many cases making it somewhat difficult to determine exactly what the impact from a specific setting change will create for the system.

 

For some types of sporting events a single AF servo setup will pretty much do just about everything for you but soccer isn't one of those types of events.  There are so many different scenarios in this game which is played on a very large field that you basically need to choose the best set of AF servo parameters for the situation you expect (or plan to shoot) the most and then keep in mind the limitations of that parameter set for other situations and compensate by your input as the photographer helping the system to provide the desired results. 

 

In soccer situations when there is a lot of passing going on then fast lock on the new subject is more important than having the system ignore "interference".  Last Spring I was shooting mainly high school varsity soccer with a lot of long ball control runs by a single player but I also shot a few of the "puppies" games that the coach ran to teach pre-school kids the basics of soccer.  Getting photos of the young kids was almost like shooting a pro game because a LOT of passing was going on but in this case the "passes" were often to the opposing team and the best AF setup was to speed acquistion of the next desired subject.

 

Rodger


Thanks, Rodger.  That does seem to confirm the way I was comprehending the manual's explanation.  And, it does make sense, which is always a nice side benefit.  :-)   I primarily shoot gymnastics and football, but more recently have been doing many other sports as well, so it's really fun to keep learning!  The 1DXII is a beast.  I bet it will be years before I come close to being a worthy operator who is truly leveraging all its features!  I learn something new every time I dive back into the manuals. 

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Posts: 13,181
Registered: ‎12-07-2012

Re: AF Accel./decel. tracking Question

Coach, 

I have found it is one thing to understand the functions that the 1Dx series can do and quite another to actually put it into practice.  You may know how to catch a football or hit a baseball but that does not equate to the fact of actually doing it.

Again practice, practice and practice.

EOS 1DX and 1D Mk IV and several lenses!
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Posts: 10,587
Registered: ‎08-13-2015

Re: AF Accel./decel. tracking Question

I am going to say that you are way over thinking this.  Stop worrying about the nuances of AF tracking for now.  If you are new at this, then you will have a harder time tracking subjects than the camera will.  Those settings only apply in AI Servo mode.

 

Leave the AF tracking mode set to default.  In fact, reset the camera back to factory defaults, and discover the exposure triangle and depth of field.  However, there is one change you may want when using AI Servo mode.  Set your image priority settings for focus priority on have a go at it.

----------------------------------------------------------------------------------------------------------------------------------------------------------

"Doctor told me to get out and walk, so I bought a Canon."
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Frequent Contributor
Posts: 95
Registered: ‎01-30-2018

Re: AF Accel./decel. tracking Question


@ebiggs1 wrote:

Coach, 

I have found it is one thing to understand the functions that the 1Dx series can do and quite another to actually put it into practice.  You may know how to catch a football or hit a baseball but that does not equate to the fact of actually doing it.

Again practice, practice and practice.


Thanks, Ernie.  I enjoy nothing more than practicing!!!  

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Frequent Contributor
Posts: 95
Registered: ‎01-30-2018

Re: AF Accel./decel. tracking Question


@Waddizzle wrote:

I am going to say that you are way over thinking this.  Stop worrying about the nuances of AF tracking for now.  If you are new at this, then you will have a harder time tracking subjects than the camera will.  Those settings only apply in AI Servo mode.

 

Leave the AF tracking mode set to default.  In fact, reset the camera back to factory defaults, and discover the exposure triangle and depth of field.  However, there is one change you may want when using AI Servo mode.  Set your image priority settings for focus priority on have a go at it.


Thanks, Waddizzle.  I'm actually not new to sports shooting.  Been doing it with Canon gear for about 13 years.  The 1DXII is what's new.  The AF system + burst shooting is why I bought it.  Gymnastics taxes the system as hard as any sport out there due to the difficult shooting conditions.  I enjoy learning about the settings before putting them into practice.  I've already taken huge advantage of the tracking sensitivity and the af point switching sensitivities.  Just learning more about this final one. 

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