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Archive 2012 · Zone AF vs. one select point AF
  
 
PetKal
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p.1 #1 · Zone AF vs. one select point AF


Let us attempt to pool some practical experience with Canon camera auto focussing using Zone AF and single selected point AF (with or without expansion).

When do you use one mode or the other, why is that so, and what lessons have you learned about them ?

Since this is not a topic suitable for a forumography type discussion , the question is primarily directed at the users of 7D, 5DMkIII and 1DX (and any other EOS camera that has zone AF, if I've missed them).



Aug 01, 2012 at 03:48 PM
sritri
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p.1 #2 · Zone AF vs. one select point AF


Peter - I have found the Zone AF work very well when I am dug in the marsh trying to get the small Green Herons catch food. These guys seems to stretch their necks a long distance from their perch when they see movement below and when using AI Servo Single point I would lose focus as their eyes and beak would go out of the frame of composition.

With Zone AF I am able to retain focus relative to the movement but I need to master the art of panning to get more keepers

I use Single point for anything and everything else.



Aug 01, 2012 at 04:25 PM
PetKal
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p.1 #3 · Zone AF vs. one select point AF


sritri wrote:
Peter - I have found the Zone AF work very well when I am dug in the marsh trying to get the small Green Herons catch food. These guys seems to stretch their necks a long distance from their perch when they see movement below and when using AI Servo Single point I would lose focus as their eyes and beak would go out of the frame of composition.

With Zone AF I am able to retain focus relative to the movement but I need to master the art of panning to get more keepers

I use Single point for anything
...Show more

Shreeni, that is an excellent example for zone AF.



Aug 01, 2012 at 04:31 PM
Ian.Dobinson
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p.1 #4 · Zone AF vs. one select point AF


Peter, as I'm nowhere near the AF targeting expertise that most of you lot are (ie I can't keep a single AF point on a target smaller than a barn door ) I absolutly LOVE zone AF on my 7D . It's probably the 1 thing that makes it so so much better to use than my old 40D . Even I can keep that big block of 9 points on target
I also like the ability to choose different Zones depending on the orientation you are shooting

I don't know what the zones are like on the 5D3 / 1Dx but my guess is they can only be even better . Just wish I could A. Afford the 5D3 and B. the 7D update (whenever that is ) keeps the crop and gets the new AF system



Aug 01, 2012 at 04:59 PM
Tim Kuhn
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p.1 #5 · Zone AF vs. one select point AF


I use single point for everything and only because I'm lazy. True most of the shooting I do is suited for single point, IF and stationary birds. But I have adapted single point to macro, florals, people and landscape. Am I saying that is the best way to do things. No. That's just the way I do it.

Tim



Aug 01, 2012 at 05:08 PM
PetKal
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p.1 #6 · Zone AF vs. one select point AF


Ian.Dobinson wrote:
Peter, as I'm nowhere near the AF targeting expertise that most of you lot are (ie I can't keep a single AF point on a target smaller than a barn door ) I absolutly LOVE zone AF on my 7D . It's probably the 1 thing that makes it so so much better to use than my old 40D . Even I can keep that big block of 9 points on target I also like the ability to choose different Zones depending on the orientation you are shooting

I don't know what the zones are like on the 5D3 /
...Show more

Ian, in retrospect, I might have not given the Zone AF mode enough of a chance when I got 7D.
I might have given up on it too quickly.



Aug 01, 2012 at 05:50 PM
PetKal
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p.1 #7 · Zone AF vs. one select point AF


Tim Kuhn wrote:
I use single point for everything and only because I'm lazy. True most of the shooting I do is suited for single point, IF and stationary birds. But I have adapted single point to macro, florals, people and landscape. Am I saying that is the best way to do things. No. That's just the way I do it.

Tim


Tim, I have also been a single AF point (with auto expansion) practitioner for years.
However, 1DX has shown me that there could be some merit in Zone AF, particularly when the point switching speed is dialed up to +1 or +2. With smaller targets against empty or "non-threatening" background, and where there is enough DoF to cover the entire target, I feel the zone AF deserves some closer looking into.



Aug 01, 2012 at 05:57 PM
uz2work
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p.1 #8 · Zone AF vs. one select point AF


I have not used either the 5D Mark III or the 1DX, but I do have a 7D, which has the zone focus option, and a 1D Mark IV, which has what is called an area focus option similar to zone focus.

With both of those bodies, my preferred focus option in most situations is still a single manually selected focus point expanded to surrounding points, and, if the background is especially busy, I'll limit the focus to just the single manually selected point. Even though the 7D zone focus and 1D Mark IV area focus both seem to work better than the auto selection options on the 1D Mark II or 1D Mark III, my experience is still that, given enough opportunities, they will still eventually let me down. Thus, I still trust my ability to keep the focus point on the subject more than I trust the camera's ability to guess correctly what the subject on which I want the camera to focus is.

Perhaps, if I spent more time experimenting with the 7D zone focus and 1D Mark IV area focus, I might know better just why they seem to work well in sometimes and why they fail in other times, but I pretty much gave up on those options and have been more than happy with the results I get using, depending on the situation, either a single manually selected point point, or a manually selected point expanded to surrounding points.

Les



Aug 01, 2012 at 08:24 PM
PetKal
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p.1 #9 · Zone AF vs. one select point AF


Thanx, Les, I didn't know 1DMkIV had that area AF feature. Is the AF point switching speed adjustable on MkIV ?
(In their 5DMkIII and 1DX literature on zone AF, Canon does say that higher AF point switching speeds tend to increase the likelihood of AF going astray.)



Aug 01, 2012 at 09:10 PM
uz2work
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p.1 #10 · Zone AF vs. one select point AF


PetKal wrote:
Thanx, Les, I didn't know 1DMkIV had that area AF feature. Is the AF point switching speed adjustable on MkIV ?


No, there is no option to "switch speeds".

I get the feeling, with more and more sophisticated options, whether they be the ones on the 7D or 1D Mark IV or the even larger array of options for the 5D Mark III and 1DX, that the "best" choice could well very from one shot to the next, and, unless the user is both steeped in knowledge about each option and prepared to change options frequently when appropriate, that it will often be the case that the option being used is less than the optimal one. My thinking with regard to AF options is consistent with my thinking about custom functions, in general. Default settings are default settings for a reason, and that reason is that they are the ones that should work in most situations. When changes are made from those default settings, there should be a specific reason for doing so. Further, I'm confident that many users make an excellently functioning camera into one that does not appear to function well by changing custom functions and focus options in a willy-nilly fashion.

Les



Aug 01, 2012 at 09:33 PM
 

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PetKal
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p.1 #11 · Zone AF vs. one select point AF


Well, yes, I have never been very happy with different AF settings, or rather, the way Canon explains them, and then trying to see how they work in practice.
Now, with 1DX and 5DMkIII, Canon has probably tried to make it easy for the camera user by providing six AF tracking scenarios-recipes based on different motion types, yet I struggle with that concept as well as its application. However, that is probably a different topic.



Aug 01, 2012 at 09:50 PM
StillFingerz
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p.1 #12 · Zone AF vs. one select point AF


Peter, since I've none of the zone AF bodies you've mentioned, but may in the future (7D or 5D3), I'll ask a simpleton question. My 40D(3 choices) and 50D(2 choices) have C functions on the mode dial; the 7D and 5D3 (3 choices) that I use to help me quickly choose between predetermine shooting situations depending on my best guesses for a day's shoot.

Once you figure out the zone choices that work best given cluttered vs non-cluttered backgrounds, can you use the C functions to preset AF, along with all the other settings (WB, Exposure Comp, fill flash, etc.)?

Single point AF is all I use right now, I'm reading about the AF of the 7D, 5D3 just to get ready...any references you or others might point me to would be much appreciated. I can catch a surfer on occasion, even a rare BIF and if zone will help me I may start with the 7D or it's upgrade, as the 5D3 is a ways off budget wise. Don't mean to hijack the thread...

Jerry



Aug 01, 2012 at 10:28 PM
Pixel Perfect
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p.1 #13 · Zone AF vs. one select point AF


Zone AF on the 7D works very well against mostly clear skies and is great for barn swallows. Keen to see it in action on the 5D III. I don't use it much however and still prefer single or single with expansion. On the 1D IV haven't had a chance to try the 18pt expansion option which will track a subject across the AF area after first acquiring a lock with the chosen point. It's faster than auto AF point selection.


Aug 01, 2012 at 11:54 PM
PetKal
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p.1 #14 · Zone AF vs. one select point AF


StillFingerz wrote:
Once you figure out the zone choices that work best given cluttered vs non-cluttered backgrounds, can you use the C functions to preset AF, along with all the other settings (WB, Exposure Comp, fill flash, etc.)?

Single point AF is all I use right now, I'm reading about the AF of the 7D, 5D3 just to get ready...any references you or others might point me to would be much appreciated. I can catch a surfer on occasion, even a rare BIF and if zone will help me I may start with the 7D or it's upgrade, as the 5D3 is a
...Show more

Jerry, perhaps someone else can chime in with that C function because I've never used it.
I think zone AF can work well if the background doesn't compete against your target for AF's "attention".
That means the background is either "smooth", or it is very distant.
Also, for close target zone AF, gotta have plenty of DoF because you have no control on the parts of the target that the camera will focus on. In theory it should AF on the closest contrast, but in practice it is pretty scattered.

Also, see those two illustrations below. They are full frames taken with 1DX + 400 f/5.6 this evening.


Edited on Aug 02, 2012 at 06:11 PM · View previous versions



Aug 02, 2012 at 01:17 AM
Tim Kuhn
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p.1 #15 · Zone AF vs. one select point AF


PetKal wrote:
Tim, I have also been a single AF point (with auto expansion) practitioner for years.
However, 1DX has shown me that there could be some merit in Zone AF, particularly when the point switching speed is dialed up to +1 or +2. With smaller targets against empty or "non-threatening" background, and where there is enough DoF to cover the entire target, I feel the zone AF deserves some closer looking into.


Thanks for the thoughts Peter. Now if I can overcome my inertia I'll give it a shot

Tim



Aug 02, 2012 at 01:29 AM
mptnest
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p.1 #16 · Zone AF vs. one select point AF


Peter, great question. One that is discussed quite frequently between several of us 7D users. I Personally switch between three AF modes depending on the crieria of distance, movement and background. For stationary shots, spot focus is my go to mode. For IF shots, shooting long lens (500-700mm)... For "sky shots", nine point mode is what I use for fast focus acquisition. This stops the lens from far focusing to infinity. As the IF gets closer. I switch to single point or spot mode (depending on distance). That way I'm ready for a fishing shot or if the background becomes cluttered.

When the background is cluttered and the IF is further away, I'll start with spot mode, then switch to single point as it gets closer. When the background/foreground gets really cluttered for IFs, like hummingbirds, I only use spot focus. My 7D hardly ever leaves AI focus, even on stationary shots as it does not effect the focusing accuracy for me.

I don't find much luck with zone AF on a cluttered background. I always wonder why the AF point expansion mode was put on the 7D. That mode has a keeper rate of zero for me.



Aug 02, 2012 at 01:40 AM
PetKal
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p.1 #17 · Zone AF vs. one select point AF


Tim, it's similar here, I mean the inertia, but 1DX is forcing me to go back and evaluate everything properly from the ground up.

So far I have concluded the following re 1DX AF.
(1) Zone AF with (+1) or (+2) AF pt. switching speed works very well on small, fast and erratic targets which move against a "non-threatening" background.
(2) Single AF point (with expansion) works very well to focus on targets which are moving (flying) against a busy background. I figure 1DX is at least 100% better that way than 1DMkIIN or 1DsMkII.
(3) Extreme defocus handling is the best I have seen on any camera so far, I'd say at least 100% better than 1DMkIIN or 1DsMkII. For example, for the first time ever I am able to use the full focusing distance limiter range on 400 f/5.6, and have only a minor loss in AF responsiveness.
This particular performance improvement may turn out to be a big help with long lenses such as 600 f/4 and 800L which have an intrinsically huge defocus range.



Aug 02, 2012 at 01:45 AM
PetKal
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p.1 #18 · Zone AF vs. one select point AF


mptnest wrote:
Peter, great question. One that is discussed quite frequently between several of us 7D users. I Personally switch between three AF modes depending on the crieria of distance, movement and background. For stationary shots, spot focus is my go to mode. For IF shots, shooting long lens (500-700mm)... For "sky shots", nine point mode is what I use for fast focus acquisition. This stops the lens from far focusing to infinity. As the IF gets closer. I switch to single point or spot mode (depending on distance). That way I'm ready for a fishing shot or if the background becomes
...Show more


Al, if you are able to change the AF area on the fly, then you are a better man then I am . All I can do on the fly is tweak the shutter speed/aperture.

A question: since the spot AF slows down the camera response, how do you find that for fast BIF ?



Aug 02, 2012 at 01:57 AM
mptnest
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p.1 #19 · Zone AF vs. one select point AF


I don't see an issue with response time in spot. The only issue I have sometime is focus acquisition issues causing the camera to hunt a little quicker. You gotta stay on target; but that's my job, not the camera's I figure.


Aug 02, 2012 at 02:03 AM
mptnest
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p.1 #20 · Zone AF vs. one select point AF


Petkal wrote:
All I can do on the fly is tweak the shutter speed/aperture.


Peter, unless the lighting changes drastically, 1 to 2 stops, i don't adjust my exposure much on the fly. I find it easier to adjust exposure in post than I can focus. Am I thinking correctly on that?



Aug 02, 2012 at 02:21 AM
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