AI Servo - Number of Focus Points

[Waddizzle]

I am basically a still photographer.  Apparently, my renewed interest in photography has created a reputation of me being some sort of photography guru.  HA-HA    So, folks with smartphone cameras have begun asking me to come and take pictures for them of this, that, or some other event.  No weddings, just Little League games, and the like.

Shooting stills means using One-Shot focusing mode, which may not  be best for moving subjects.  So, I've been exploring and experimenting with AI Servo mode.  Which, brings me to a question that I cannot answer. 

Does it matter if I am using just the center focus point, or should I need to turn of manual point selection altogether? 

So far, my experiments have been inconclusive.  My shots are in focus, but I am attributing that to pre-focusing.  I get much better results by pre-focusing, than when I don't.  Keeper rate is pretty much the same with manaul AF point selection, no matter if I use One-Shot or AI Servo modes. 

I pre-focus on a player, or where I expect a player will be: i.e.; focusing on the base ahead of the base runner.  I can get good shots, like the above play at third base.  [the shot has been cropped to remove faces and team information]

But, forget about refocusing on an outfielder chasing down a ball.  The kid is running, so One Shot doesn't work out very well, but neither has AI Servo with only the center point, manually selected.  Turing on all of the AF points, 9 in a 6D, results in the camera frequently focusing where it wants, not where I want it to.

I guess I am saying that it seems that I have not been able to have the camera actuallly track a moving subject.  So, do I need to turn on all AF points, in order to make it track in AI Servo, or not?  For me, I am having bad luck relying on automatic AF point selection to pick out the running kid in the outfield, instead of a background tree, or something.

[jrhoffman75 · Accepted solution]

This is an excerpt from a 1D Mark IV guide by canon, but the concept is the same for all cameras. AI Servo is doing math, and you need to give it a little time to compute.

[ebiggs1 · Accepted solution]

"I hope a 6D mark II ..."

"BTW, I am 6'8" and 220 lbs."

If anybody I have ever met should get a 1 series it is you.  Your size is a match.  I can't imagine you are comfortable with a Rebel.  Or even a xD series for that matter.  My size and the total lack of being impressed by a 6D was just another plus sign for a 1 series.  If you can't drop the coin on a 1Dx look for a clean 1D Mk IV.  Once you go 1 series, you will never go back. That's a fact, Jack!  IMHO, of course, as always.

[ebiggs1]

You know my answer.  Use just the center point. All the pros I know, use just the center or they pre-focus.  Remember I have 65 I could use but I use just the center 98% of the time.  If you are always following the action, you will never be a great sports photographer.  Guru or not ! IMHO, of course as always.

My 1D Mk IV can not focus as fast as it can shoot. So, it is a moot point there.  Your 6D even though it is a slower camera probably can not focus as fast as it can shoot either.  That is if you are using hi-speed shooting which I assume you are.  Singles, use center point.

[Waddizzle]

"You know my answer.  Use just the center point. All the pros I know, use just the center or they pre-focus."

Yeah, manually select the just the center point, CP, I kmow.  But, is that using One-Shot or AI Servo with moving subjects?  Like I said, I can to really well pre-focusing, and anticipating movement. 

My problem is quickly switching from one subject to the next subject, like during an outfiled catch, and throw to the plate.  I get best results pre-focusing the manaul CP selection in One Shot mode, but that means not moving the camera.  I get the best results when I am moving the camera with automatic AF point selection using AI Servo mode. 

Is there no happy medium?  Manual AF points and AI Servo has a lower keeper rate.  Automatic AF points and One-Shot has a lower keeper rate, too.  I have found I have to choose between a relatively staionary camera mode, or a moving and tracking camera mode.  The latter mode means switching subjects is very finicky.  The former mode is relatively easy to switch, with BBF, but I have to pick my new pre-focus point, which is a hit or miss proposition.

[RobertTheFat]

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@ebiggs1 wrote:

You know my answer.  Use just the center point. All the pros I know, use just the center or they pre-focus.  Remember I have 65 I could use but I use just the center 98% of the time.  If you are always following the action, you will never be a great sports photographer.  Guru or not ! IMHO, of course as always.

My 1D Mk IV can not focus as fast as it can shoot. So, it is a moot point there.  Your 6D even though it is a slower camera probably can not focus as fast as it can shoot either.  That is if you are using hi-speed shooting which I assume you are.  Singles, use center point.

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Ernie, I've never understood your preoccupation with using only the center point. It's a fairly well accepted principle of composition that the main subject shouldn't always be centered in the frame. So you're left with either re-positioning the camera after focusing or focusing away from the subject. Why either of those options is A Good Thing requires further explanaton which I don't think you've ever provided.

[Waddizzle]

"Ernie, I've never understood your preoccupation with using only the center point. It's a fairly well accepted principle of composition that the main subject shouldn't always be centered in the frame. So you're left with either re-positioning the camera after focusing or focusing away from the subject. Why either of those options is A Good Thing requires further explanaton which I don't think you've ever provided." 

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If someone were using just a single point, assuming we're talking handheld here, I cannot understand why someone would use anything other than the center point.  I lock focus, and recompose a shot all the time.  I find it to be the best method to use for "One Shot" mode. 

When shooting sports, I don't think composition is as much of a priority, as it is simply getting the shot.  Using just the center point seems to be the fastest way to focus on a moving subject, or any subject.  Using the same modus operandi for non-action shooting scenarios makes sense to me. 

Overall, I'd say the "center point only" practice is consistent with the "K.I.S.S." principle, and a principle that I wholeheartedly agree with..  My point in this thread has been about what AF point setting is best for "AI Servo" mode..  Ernie's reply seems consistent with the "K.I.S.S." approach.  The best answer seems to be use the center, but with AF Assist points, wihch my 6D lacks.

[ebiggs1]

As one gains experience actually doing this and shooting, I believe they, too, will come to the realization that the center point is best. That's why it's what the high dollar pros use.  They know what works.

In this area of photography we agree. There is common ground.  

[ebiggs1]

"Ernie questioned my sports knowledge."

Actually this isn't correct either. At least it isn't as I wanted it to be understood.  I simply questioned your sports knowledge as it pertains to photography.  I am sure Alex Gordon, our (the Royals) multi-Gold Glove outfielder knows baseball but I doubt he knows how to photograph it.  Just my take and of course I could be wrong.

[Waddizzle]

"I am sure Alex Gordon, our (the Royals) multi-Gold Glove outfielder knows baseball but I doubt he knows how to photograph it. " 

You're still talking about knowing your gear, and how to use it, whether you realize it or not, more than anything else. 

Most of the sports photographers I have known were always trying to pick your brain to learn how athletes see their own particular sport.  The best guys seemed to realize that the best shots were about what some guys used to refer to as the "perspective of the objective", particularly from the first person perspective of the athlete.

That approach is what is drives the classic, "over the shoulder" view of how a pitcher sees home plate, and the batter, when he is throwing a pitch.  Ditto for the "batter's perspective" shots from behind plate.  Ditto for the shots where an infielder is seemingly throwing the ball directly into the camera.  Ditto for shots that look along the foul lines, which are representative of the umpire's perspective. Many baseball shots give a "from the dugout view" of the action.

Football.  Ditto for the shots from behind the kickoff, or the receiving, team.  Shots down the goal line are a textbook example of "perspective of the objective" appproach.  Ditto for shots down the line of scrimmage.  In recent years, they have introduced "sky cams" that hover over the field to give the viewer a perspective what it looks like to be on the field. 

I think you would be stunned about what athletes could teach a photographer about how to photograph their particular sport.

[ebiggs1]

"You're still talking about knowing your gear, and how to use it, whether you realize it or not, more than anything else."

Thanx for clearing that up for me. I was so confused but now I know where I have gone wrong.

"I think you would be stunned ..."

Yes, I am "stunned" but possibly not for reasons you mentioned.

[diverhank]

The difference between one shot and AI Servo is that the camera continues to track the target once you achieve focus and keep the focus button/shutter depressed.  For a single focus point, as you observed, you must keep that point on the moving target all the time then the camera will focus on it automatically.

In practice, with Canon 9 point cameras, I find that AI Servo effectiveness is very limited. With more points, you can select center AF point with either 9 assists (5D3) or 14 assist points (7D2) and AI Servo really sings for the occasion that I can't keep the center point on target.  I'm primarily a BIF shooter and I use AI Servo 99% of the time.