Struggling to keep Focus in AFC

[astroNikon]

I'll add a bit.
When I first bought my d7000 and started using it for my kids sports I had all kinds of focusing problems.

Learning and practicing the focusing system on just birds in the backyard really improved my knowledge of it.
Then learning the idiosyncrosies of the AF system on certain lenses, such as my 80-200/2.8 AF-D - this is the old screw drive type lenses, not the AF-S with a built in motor.

With the AF-D lenses I will keep pressing the Release half way as the action continues to keep focus. If I waited too long, even though I would keep the object in the AF focusing area, when I pressed the release it would hunt before reacquiring the subject. (See TheLost info above too).

But over time I've really learned how to use the AF system for sports of wildlife birds or anything fast moving. It will take time and practice. Just sit on your porch and shoot birds flying around and learn each mode and option.

I also made sure my AF modes were set to "Release" vs "Focus" which meant you can take pictures OOF. You just have to learn your camera and lens and not do that lol

 

[MGRPhoto]

As I said Dynamic Area will not "follow" the subject from one focus point to another.
[..]
It will use data from surrounding focus points to try and keep the subject in focus if the subject leaves the selected focus point for only a brief moment.

Um.. it does 'follow' the subject..

If the subject leaves the selected focus point for more than that brief period of time (not sure if there is a set time or what that time would be) it will attempt to refocus on whatever now happens to be in the focus point you originally selected.

That's what i said.. Its like single point focus... with a brian. If you have Dynamic 9 point selected.. it will only follow the target in those 9 points. Dynamic 21 point increases the 'zone'.. Dynaimc 39 uses all the focus points (on the D7000).

The time it stays 'locked on' is defined by the option "Focus Tracking with lock-on" (Menu option a3). It lets you configure how long the subject can be 'lost' before it re-acquires a new target.

In real world shooting.. 9 point focus with a short to normal (1 - 3) tracking time works best. The more Dynamic points you have the more the camera can get confused.

95% of my shooting is Sports/Action.. I have tens-of-thousands of pictures taken with the D7000 (and i'm catching up with the D7100). I also have [who knows how many] pictures taken with older cameras that only had 'single point focus' (D70 & film bodies).

Dynamic auto focus is the da-bomb (is that the words kids use now?)

You should check your ego at the door and just admit that you're wrong because that is VERY misleading terminology and will most certainly confuse people who are trying to learn how to use the AF system and read your post. Saying Dynamic AF "follows" the subject is absolutely not a true statement. It does nothing of the sort. It does exactly what I described as backed up by Nikon's own documentation: Nikon | Imaging Products | Digital SLR Camera Basics | AF-Area Mode (Viewfinder Photography)
And copy/paste from the D3s manual: "If the subject briefly leaves the selected focus point, the camera will focus based on information from surrounding focus points."
The way you're describing it there is 0 difference between Dynamic AF and 3D tracking. Follow Subject = Tracking Subject = Subject moving from focus point to point. Dynamic AF will never move focus points.

When you say something like "follow the target in those 9 points" there is no way for someone to interpret that other than to imply that the 9 points can be used to focus on the subject. As in the subject leaving the selected focus point and the next focus point picks up and will now be the primary focus point. That is not the case. Only 1 point can be used to focus the subject and that point cannot move to another point.

Also you're saying that Focus tracking with lock-on effects Dynamic AF and that is ONLY true in the case of DISTANCE. It sets the interval for how long it waits to refocus based on the distance from the subject not whether it leaves the focus point or not.
Again quoted from the D3s manual: "Focus tracking with lock-on controls how the camera responds to abrupt changes in focus distance."

 

[TheLost]

You should check your ego at the door and just admit that you're wrong because that is VERY misleading terminology and will most certainly confuse people who are trying to learn how to use the AF system and read your post. Saying Dynamic AF "follows" the subject is absolutely not a true statement. It does nothing of the sort. It does exactly what I described as backed up by Nikon's own documentation: Nikon | Imaging Products | Digital SLR Camera Basics | AF-Area Mode (Viewfinder Photography)
And copy/paste from the D3s manual: "If the subject briefly leaves the selected focus point, the camera will focus based on information from surrounding focus points."
The way you're describing it there is 0 difference between Dynamic AF and 3D tracking. Follow Subject = Tracking Subject = Subject moving from focus point to point. Dynamic AF will never move focus points.

When you say something like "follow the target in those 9 points" there is no way for someone to interpret that other than to imply that the 9 points can be used to focus on the subject. As in the subject leaving the selected focus point and the next focus point picks up and will now be the primary focus point. That is not the case. Only 1 point can be used to focus the subject and that point cannot move to another point.

Also you're saying that Focus tracking with lock-on effects Dynamic AF and that is ONLY true in the case of DISTANCE. It sets the interval for how long it waits to refocus based on the distance from the subject not whether it leaves the focus point or not.
Again quoted from the D3s manual: "Focus tracking with lock-on controls how the camera responds to abrupt changes in focus distance."

I'm not sure what your smoking... but Nikon's documentation backs up what i said.

If the target/subject leaves the selected focus point the camera will use the surrounding points (9/21/39 points depending on Dynamic mode) to adjust focus on the target.. basically FOLLOWING the the selected target on those 9/21/39 points. Does the 'main focus point' move? No.. however the camera MAY use one of the 9/21/39 points if it thinks the target has left the original focus point.

Say your shooting a runner on a track.. Your camera is set to Dynamic 21 point focus.. If the runner falls right as you take the picture and he/she drops off your focus point the camera will 'DYNAMICALLY' select one of the 21 points it thinks the runner has moved to. Essentially 'following' the runner in the 21 points while focus is engaged.

If somebody runs through your field of view.. While you have AF engaged on your target the "Focus tracking lock-on" time will decide if it stays with your original runner or picks up the new runner.

*edit*.. hows this (taken from the link i posted to earlier):

"[you] focus on the subject with the center point of the array and continue holding the Shutter Release Button in the half press position. While holding, any movement of the subject within the array is tracked dynamically, allowing any point
within the array to take over as the primary point of focus. As you follow the subject and attempt to keep the array on top of it, the array is acting as a buffer to compensate for any lead or lag that you may have in tracking."

 

[Derrel]

It's weird...when I first saw the title of this post, "Struggling to keep Focus in AFC," I thought it might have been a post about AFC Champion Denver's horrific loss in the Super Bowl, and how their humiliating 43-8 loss to NFC Champion Seattle might affect this year's off-season...or the AFC's struggles, what with the way the Patriots crumbled so easily in the AFC divisional title game....

 

[MGRPhoto]

You should check your ego at the door and just admit that you're wrong because that is VERY misleading terminology and will most certainly confuse people who are trying to learn how to use the AF system and read your post. Saying Dynamic AF "follows" the subject is absolutely not a true statement. It does nothing of the sort. It does exactly what I described as backed up by Nikon's own documentation: Nikon | Imaging Products | Digital SLR Camera Basics | AF-Area Mode (Viewfinder Photography)
And copy/paste from the D3s manual: "If the subject briefly leaves the selected focus point, the camera will focus based on information from surrounding focus points."
The way you're describing it there is 0 difference between Dynamic AF and 3D tracking. Follow Subject = Tracking Subject = Subject moving from focus point to point. Dynamic AF will never move focus points.

When you say something like "follow the target in those 9 points" there is no way for someone to interpret that other than to imply that the 9 points can be used to focus on the subject. As in the subject leaving the selected focus point and the next focus point picks up and will now be the primary focus point. That is not the case. Only 1 point can be used to focus the subject and that point cannot move to another point.

Also you're saying that Focus tracking with lock-on effects Dynamic AF and that is ONLY true in the case of DISTANCE. It sets the interval for how long it waits to refocus based on the distance from the subject not whether it leaves the focus point or not.
Again quoted from the D3s manual: "Focus tracking with lock-on controls how the camera responds to abrupt changes in focus distance."

I'm not sure what your smoking... but Nikon's documentation backs up what i said.

If the target/subject leaves the selected focus point the camera will use the surrounding points (9/21/39 points depending on Dynamic mode) to adjust focus on the target.. basically FOLLOWING the the selected target on those 9/21/39 points. Does the 'main focus point' move? No.. however the camera MAY use one of the 9/21/39 points if it thinks the target has left the original focus point.

Say your shooting a runner on a track.. Your camera is set to Dynamic 21 point focus.. If the runner falls right as you take the picture and he/she drops off your focus point the camera will 'DYNAMICALLY' select one of the 21 points it thinks the runner has moved to. Essentially 'following' the runner in the 21 points while focus is engaged.

If somebody runs through your field of view.. While you have AF engaged on your target the "Focus tracking lock-on" time will decide if it stays with your original runner or picks up the new runner.

*edit*.. hows this (taken from the link i posted to earlier):

"[you] focus on the subject with the center point of the array and continue holding the Shutter Release Button in the half press position. While holding, any movement of the subject within the array is tracked dynamically, allowing any point within the array to take over as the primary point of focus. As you follow the subject and attempt to keep the array on top of it, the array is acting as a buffer to compensate for any lead or lag that you may have in tracking."

This is absolutely incorrect. Read the documentation. Dynamic AF will never select a different Auto-focus point. Absolutely never. This can't be more wrong and I'm not sure how to make you understand. You are literally saying that Dynamic AF and 3D tracking are exactly the same. And using the word tracked in the italicized portion of your posts is completely incorrect as well. Nikon intentionally avoids that word in all descriptions of Dynamic AF because that IS NOT what it is doing. I do however like the very last sentence describing Dynamic AF as a buffer. That it is. I'm surprised you can get some thing so incorrect and something correct describing the same thing one sentence after another. The italic part I put in bold is the definition of 3D tracking.

 

[TheLost]

It's weird...when I first saw the title of this post, "Struggling to keep Focus in AFC," I thought it might have been a post about AFC Champion Denver's horrific loss in the Super Bowl, and how their humiliating 43-8 loss to NFC Champion Seattle might affect this year's off-season...or the AFC's struggles, what with the way the Patriots crumbled so easily in the AFC divisional title game....

Crap.. Derrel.. now your telling me i'm wrong because i'm a Seahawk fan and don't like the Patriots? I give up!!!

 

[sk66]

The problem is with the AF delay setting (menu item A3 on my D800). This determines how long the camera waits to refocus if the selected AF point falls on a "new subject". I.e. in AF-C dynamic with the center point selected: If the AF is tracking the subject onto other points because the active (selected) point is not on the subject the camera will refocus on the active (selected) point. With the delay set low it will essentially stop tracking as long as the active (selected) point is on something that can be focused on (i.e. it will track a bird in clear sky, but not w/ a BG of trees). Set very high, and it will refuse to refocus on something else for quite some time... this can be problematic if you miss the focus initially which requires releasing the focus and restarting it.

FWIW, newer Nikon's are NOT using only the active (selected) focus point in dynamic mode. They are using the selected point AND any of the points immediately surrounding it, whichever one has the best conditions for AF lock (contrast). I didn't notice the behavior on the D7000 (or D200/300/3/3s), but I don't have one to test. Both my D4 and D800 behave this way. I may have just failed to recognize it earlier, or it may be a recent change.

 

[TheLost]

"[you] focus on the subject with the center point of the array and continue holding the Shutter Release Button in the half press position. While holding, any movement of the subject within the array is tracked dynamically, allowing any point within the array to take over as the primary point of focus. As you follow the subject and attempt to keep the array on top of it, the array is acting as a buffer to compensate for any lead or lag that you may have in tracking."

This is absolutely incorrect. Read the documentation. Dynamic AF will never select a different Auto-focus point. Absolutely never. This can't be more wrong and I'm not sure how to make you understand. You are literally saying that Dynamic AF and 3D tracking are exactly the same. And using the work tracked in the italicized portion of your posts is completely incorrect as well. Nikon intentionally avoids that word in all descriptions of Dynamic AF because that IS NOT what it is doing. I do however like the very last sentence describing Dynamic AF as a buffer. That it is. I'm surprised you can get some thing so incorrect and something correct describing the same thing one sentence after another. The italic part I put in bold is the definition of 3D tracking.

Wow.. Now who's ego is acting up?

3D tracking CHANGES the selected focus point as the target moves around the screen. It uses a totally different predictive algorithm to track the position of the subject. It also uses more data (color, light, distance, movement) to track the subject.

Why don't you translate this for us then..
http://nps.nikonimaging.com/technical_solutions/d4_tips/autofocus/

9, 21, and 51-point dynamic-area AF
The focus point is selected manually. The camera focuses on the subject in the selected focus point when autofocus is initiated, but if the subject later leaves the selected point for brief periods, the camera will focus based on information from surrounding points.

Sure sounds like it uses the surrounding AF points if the subject leaves the selected point... effectively 'switching/changing/moving' the point in which its using to focus 'for a brief period'.

 

[MGRPhoto]

The problem is with the AF delay setting (menu item A3 on my D800). This determines how long the camera waits to refocus if the selected AF point falls on a "new subject". I.e. in AF-C dynamic with the center point selected: If the AF is tracking the subject onto other points because the active (selected) point is not on the subject the camera will refocus on the active (selected) point. With the delay set low it will essentially stop tracking as long as the active (selected) point is on something that can be focused on (i.e. it will track a bird in clear sky, but not w/ a BG of trees). Set very high, and it will refuse to refocus on something else for quite some time... this can be problematic if you miss the focus initially which requires releasing the focus and restarting it.

FWIW, newer Nikon's are NOT using only the active (selected) focus point in dynamic mode. They are using the selected point AND any of the points immediately surrounding it, whichever one has the best conditions for AF lock (contrast). I didn't notice the behavior on the D7000 (or D200/300/3/3s), but I don't have one to test. Both my D4 and D800 behave this way. I may have just failed to recognize it earlier, or it may be a recent change.

How can you make a statement like that when the manual for the camera says the exact opposite?

"[you] focus on the subject with the center point of the array and continue holding the Shutter Release Button in the half press position. While holding, any movement of the subject within the array is tracked dynamically, allowing any point within the array to take over as the primary point of focus. As you follow the subject and attempt to keep the array on top of it, the array is acting as a buffer to compensate for any lead or lag that you may have in tracking."

This is absolutely incorrect. Read the documentation. Dynamic AF will never select a different Auto-focus point. Absolutely never. This can't be more wrong and I'm not sure how to make you understand. You are literally saying that Dynamic AF and 3D tracking are exactly the same. And using the work tracked in the italicized portion of your posts is completely incorrect as well. Nikon intentionally avoids that word in all descriptions of Dynamic AF because that IS NOT what it is doing. I do however like the very last sentence describing Dynamic AF as a buffer. That it is. I'm surprised you can get some thing so incorrect and something correct describing the same thing one sentence after another. The italic part I put in bold is the definition of 3D tracking.

Wow.. Now who's ego is acting up?

3D tracking CHANGES the selected focus point as the target moves around the screen. It uses a totally different predictive algorithm to track the position of the subject. It also uses more data (color, light, distance, movement) to track the subject.

It has nothing to do with ego. It has to do with correcting misinformation to help people from being confused when they are trying to learn. Yes 3D tracking CHANGES the selected focus point. And you've said multiple times now that Dynamic AF CHANGES the selected focus point when it in fact does not. Example highlighted in red. sk66 just said the same thing. Which is wrong. Using data from a focus point and using a different focus point from the one manually selected to lock focus are not the same thing and Dynamic AF does not use a different focus point to lock focus.

 

[MGRPhoto]

Definitions from Nikon:

3D-tracking
The initial focus point is selected manually. The camera uses color information to track subjects that leave the selected focus point and selects new focus points as required.

9, 21, and 51-point dynamic-area AF
The focus point is selected manually. The camera focuses on the subject in the selected focus point when autofocus is initiated, but if the subject later leaves the selected point for brief periods, the camera will focus based on information from surrounding points.


Exactly what I've been saying. Exactly the opposite of what you guys have been saying.

 

[TheLost]

Exactly what I've been saying. Exactly the opposite of what you guys have been saying.

So how does Dynamic focus work? What does "based on information from surrounding points" mean? Explain it to me...

 

[sk66]

There are two primary differences between 3D and the other tracking modes.
In 3D it uses color information. And in 3D it does not revert to the initial AF point if the subject is lost...it instead tries to relocate the subject based on distance/color information using any of the AF points.
Oh, and a 3rd difference; 3D is slower...

 

[MGRPhoto]

Exactly what I've been saying. Exactly the opposite of what you guys have been saying.

So how does Dynamic focus work? What does "based on information from surrounding points" mean? Explain it to me...

It's using limited data from surrounding focus points to keep a "virtual" lock on the primary selected focus point so that the selected focus point can instantly resume when enough of the subject returns to the selected focus point. The surrounding focus points are essentially passing their data to the primary focus point so that the camera thinks the primary focus point is always in focus.

3D tracking on the other hand uses all available data on all points and moves the selected focus point at will. Since it's using so much more data it's also much slower and in my experience doesn't work anywhere near as well in real world usage.

Dynamic AF when used in conjunction with good hand holding/panning technique is instantaneous. With 3D tracking (even on the D3s/D4) there is noticeable lag and tendency to lose focus when the selected focus point moves to a new focus point.

 

[sk66]

It's using limited data from surrounding focus points to keep a "virtual" lock on the primary selected focus point so that the selected focus point can instantly resume when enough of the subject returns to the selected focus point. The surrounding focus points are essentially passing their data to the primary focus point so that the camera thinks the primary focus point is always in focus.

I don't know if that's true, I've never seen it in writing and that's not the way it behaves. AF continues if the selected point is not on the subject when in a dynamic mode. If you're saying that's because the selected focus point is doing it based upon information passed to it...well, that's the same result as if the other point had directly caused the change.
It also seems like that would be a daft way to design the system... it adds another step which would slow the system with no benefit.

Sometimes it's not such a good idea to read a manual word for word and believe it means exactly what it says (seems to say).... especially if it's something translated from another language.

 

[TheLost]

It's using limited data from surrounding focus points to keep a "virtual" lock on the primary selected focus point so that the selected focus point can instantly resume when enough of the subject returns to the selected focus point. The surrounding focus points are essentially passing their data to the primary focus point so that the camera thinks the primary focus point is always in focus.

So what your saying is... It uses the other focus points if the target moves.