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Author Topic: My (seemingly) never ending Focus woes ... BIF advice needed  (Read 11758 times)

bjd

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My (seemingly) never ending Focus woes ... BIF advice needed
« on: January 12, 2013, 07:49:45 AM »
Hi,
though I would start a new thread for this after hijacking this one a while ago:
Quote
http://www.canonrumors.com/forum/index.php?topic=11978.msg213260#msg213260
.

I'm trying to work methodically through the various AF settings as I could never get AF to work well with BIF (Birds in Flight) in my garden. So please bear with me. For my tests I stood by the side of the road and using low-speed continuous shooting took shots as cars came into view and crossed the field of view. Most of them will have been driving around 30-60Kph.
I assume the Camera should be able to handle this situation. Agreed?
Lens is a 70-200 F2:8 L IS II USM (Group A), IS on set to mode 2.  AF point selection set to automatic.

First point. If I set the camera to Automatic (A+), then it will focus on something nearby which is at the side of the AF points. See the picture Focus1. IMHO that is correct.

Now, if I switch to AV, now in AI-Servo AF, then it will only focus using the center points. I tried various Av and Tv settings, I could never get anything other that the center points to "Lock" (flash red).  Picture Focus2.jpg. I was using AF Case 3 here, expecting
Quote
In Case 3, the [Tracking sensitivity] parameter is set to [+1]. As a result, subjects that come into the AF points will be focused on more quickly. This setting is most
effective when subjects appear suddenly in the frame (for example photographing skiers in an alpine skiing downhill race,).
I get the effect that it has locked onto someting in the background (Focus3.jpg) and does not change focus even if the car crosses in front of the object that was in focus. Plus, it never tries to follow the car anyway. See Focus4.jpg.
This was done with the three parameters set to default and then tried to increase Tracking sensitivity to +2 without any effect. Now as the AF wont follow a car, I'm not surprised that it doesn't follow a small bird.

I'd appreciate any hints of what I may be doing wrong.

Cheers Brian
« Last Edit: March 02, 2013, 04:36:39 AM by bjd »

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My (seemingly) never ending Focus woes ... BIF advice needed
« on: January 12, 2013, 07:49:45 AM »

spinworkxroy

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Re: My never ending Focus woes with my 5DMK3
« Reply #1 on: January 12, 2013, 08:33:19 AM »
Correct me if i'm wrong, but when the camera is in Ai-Servo mode..it shouldn't flash red at all right? That IS an inconvenience with the 5D3 that many people have complained about…where it's impossible to know which points the camera is at when the red squares don't light up in Ai-Servo…
I've not actually used it before..maybe i should give it a shot and see if i face the same issues..

bjd

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Re: My never ending Focus woes with my 5DMK3
« Reply #2 on: January 12, 2013, 08:58:43 AM »
Hey,

I'm not interested in the focus point flashing, its the fact that its not picking up the movement and focusing on that. Sorry if I wasn't clear on that.

Cheers Brian

ddl

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Re: My never ending Focus woes with my 5DMK3
« Reply #3 on: January 12, 2013, 09:22:29 AM »
Do you have the center AF point selected first? If so then it's waiting for that object at the focus point to move it appears.

When using [Auto selection of 61 AF points]
during [AI Servo AF], focusing will start from
the manually selected AF point, the camera will
the automatically change the AF point selecting
from all 61 points as the subject moves.

From Bottom Left on Page 34: http://cpn.canon-europe.com/files/product/cameras/eos_5d_mark_iii/EOS_5D_Mark_III_AF_setting_guidebook.pdf
« Last Edit: January 12, 2013, 10:41:47 AM by ddl »

bjd

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Re: My never ending Focus woes with my 5DMK3
« Reply #4 on: January 12, 2013, 10:44:54 AM »
Hi ddl,
it looks suspiciously like that. But then I have to ask "what is the manually selected AF point?". In my case it always tries to select a focus point at the center and I cannot get it to focus using one of the outer points.
In A+ I can get it to focus using the rightmost column of points at 1/250th and F5.0, if I switch to M and set 1/250th and F5.6 then I can get the fourth row from the right to focus. I tried using evaluative metering too instead of spot, but that doesn't change anything.
Strange

Cheers

bdunbar79

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Re: My never ending Focus woes with my 5DMK3
« Reply #5 on: January 12, 2013, 10:52:41 AM »
1DX does the same thing.  I shot a diving meet last night and zone AF, no matter which tracking case, couldn't lock on the diver all the way through.  It would focus on stupid things in the background every 3rd shot.  I was in extremely low light, however, and that no doubt contributed to this.
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bjd

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Re: My never ending Focus woes with my 5DMK3
« Reply #6 on: January 12, 2013, 11:01:24 AM »
I especially waited for good light to try this out.
Cheers

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Re: My never ending Focus woes with my 5DMK3
« Reply #6 on: January 12, 2013, 11:01:24 AM »

ddl

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Re: My never ending Focus woes with my 5DMK3
« Reply #7 on: January 12, 2013, 11:07:28 AM »
Somehow the camera needs to know where to start which is why you have to manually pick a point over the object you want to track. After that the camera will try to keep focus on that object if it moves by selecting different AF points.

bjd

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Re: My never ending Focus woes with my 5DMK3
« Reply #8 on: January 12, 2013, 11:24:58 AM »
Quote
In Case 3, the [Tracking sensitivity] parameter is set to [+1]. As a result, subjects that come into the AF points will be focused on more quickly. This setting is most
effective when subjects appear suddenly in the frame (for example photographing skiers in an alpine skiing downhill race,).
But I have to point the focus point there, or in its general direction first, till the object hs been picked up I assume.
I had read the guide such that it would go straight for the movement. I thought that in most cases it would automatically go for the nearest object covered by a focus point.

Just tried the following. Background is clear sky, to the left is the corner of a wall. Point camera at sky,
shutter relase half pressed, now slowly pan camera to the left. No reaction till the 4th AF point column from the left is over the wall/sky line, now it has picked up the wall. As soon as it has picked it up then AF points in the 2nd and 3rd rows pick the wall up too.

So I'm still wondering why the left most column does not pick up the wall, or the post as shown in focus2.jpg?

Cheers Brian

christianronnel

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Re: My never ending Focus woes with my 5DMK3
« Reply #9 on: January 12, 2013, 11:26:29 AM »
Hi ddl,
it looks suspiciously like that. But then I have to ask "what is the manually selected AF point?". In my case it always tries to select a focus point at the center and I cannot get it to focus using one of the outer points.
In A+ I can get it to focus using the rightmost column of points at 1/250th and F5.0, if I switch to M and set 1/250th and F5.6 then I can get the fourth row from the right to focus. I tried using evaluative metering too instead of spot, but that doesn't change anything.
Strange

Cheers

First of all, having the camera in M, Av, Tv or even P mode has nothing to do with AF.  Those modes deal with exposures.  You can set the focus point with any of those modes.  Secondly, in A+ modes, you are letting the camera do all the decisions for you, both the exposure and what to focus on.  The AF cases wasn't designed for that style of shooting, if you call that a style at all.

For shooting birds in flight (or divers), I suggest to change your Selectable AF point to only cross-type.  That is located on the 4th section of the AF tab menu.  Just know that if you do this, the camera will only allow the cross-type points available for the attached lens and is normally dictated by the lens' maximum aperture.  With this selected, change the way the AI Servo works.  Go to the 2nd section of the AF tab.  Set the AI Servo 1st image priority to focus.  Set the AI Servo 2nd image priority to focus.  Now you can play with the "AF cases" if you want.  I personally leave it on Case 1.  I don't see any practical difference in any of those "Cases."

As for the red dot/focus point flashing,  this is irrelevant on AI servo mode.  If you want to see where you are focusing, you can set the AF point display during focus on 5th section of the AF tab to Selected (pre-AF, focused).

Remember, none of these will do you any good if you're shooting on the green mode.
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bdunbar79

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Re: My never ending Focus woes with my 5DMK3
« Reply #10 on: January 12, 2013, 11:34:21 AM »
Hi ddl,
it looks suspiciously like that. But then I have to ask "what is the manually selected AF point?". In my case it always tries to select a focus point at the center and I cannot get it to focus using one of the outer points.
In A+ I can get it to focus using the rightmost column of points at 1/250th and F5.0, if I switch to M and set 1/250th and F5.6 then I can get the fourth row from the right to focus. I tried using evaluative metering too instead of spot, but that doesn't change anything.
Strange

Cheers

First of all, having the camera in M, Av, Tv or even P mode has nothing to do with AF.  Those modes deal with exposures.  You can set the focus point with any of those modes.  Secondly, in A+ modes, you are letting the camera do all the decisions for you, both the exposure and what to focus on.  The AF cases wasn't designed for that style of shooting, if you call that a style at all.

For shooting birds in flight (or divers), I suggest to change your Selectable AF point to only cross-type.  That is located on the 4th section of the AF tab menu.  Just know that if you do this, the camera will only allow the cross-type points available for the attached lens and is normally dictated by the lens' maximum aperture.  With this selected, change the way the AI Servo works.  Go to the 2nd section of the AF tab.  Set the AI Servo 1st image priority to focus.  Set the AI Servo 2nd image priority to focus.  Now you can play with the "AF cases" if you want.  I personally leave it on Case 1.  I don't see any practical difference in any of those "Cases."

As for the red dot/focus point flashing,  this is irrelevant on AI servo mode.  If you want to see where you are focusing, you can set the AF point display during focus on 5th section of the AF tab to Selected (pre-AF, focused).

Remember, none of these will do you any good if you're shooting on the green mode.

I did all that stuff.  It still doesn't work that well.  My cases aren't in good light; mine are in bad lighting.  I concede that I may be asking the camera to do something unreasonable.  Even with cross-type only points in AI Servo mode, even though the diver is closer to me than anything, down throughout the dive the AF point will still go back and hit the wall, for some unknown reason, at least twice.  The reason is because the wall is grayish/white and is lighted up more than the diver.  This will confuse any AF system.  To the OP, you have to pay attention to back-lighting too.

Good discussion so far.
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christianronnel

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Re: My never ending Focus woes with my 5DMK3
« Reply #11 on: January 12, 2013, 11:42:22 AM »
I did all that stuff.  It still doesn't work that well.  My cases aren't in good light; mine are in bad lighting.  I concede that I may be asking the camera to do something unreasonable.  Even with cross-type only points in AI Servo mode, even though the diver is closer to me than anything, down throughout the dive the AF point will still go back and hit the wall, for some unknown reason, at least twice.  The reason is because the wall is grayish/white and is lighted up more than the diver.  This will confuse any AF system.  To the OP, you have to pay attention to back-lighting too.

Good discussion so far.
If you have manually selected the AF point and are subject tracking, there's no way for the camera to switch the AF points regardless of the contrast.  It will try to focus using your selected point.
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East Wind Photography

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Re: My never ending Focus woes with my 5DMK3
« Reply #12 on: January 12, 2013, 11:49:48 AM »
I agree with your assessment here.  Not all of the AF points are sensitive to the same kind of edge detection and some just are flat out not available depending on the lens used (Maximum aperture).  2.8, 4, 5.6, and in April, F8 are pretty much where things change as far as AF is concerned.  The Manual explains which AF points are used depending on the maximum Fstop of the lens (and I assume extender combination as well).  Though I have seen quite a difference in AF capability between an F5.6 lens and a 2.8 with a 2X extender at 5.6.  Even though the Fstops are essentially the same, there is some difference in the operation of AF, with the 2,8 and extender being marginally better at locking on low contrast objects.

For what it's worth, the 9 point system was much simpler to use and understand.  now with all of these different points, cross, vertical, horizontal, it makes it more complicated to implement and it's imperative that a photographer understand whats going on in that regard with a particular lens to avoid an AF trap.

Hi ddl,
it looks suspiciously like that. But then I have to ask "what is the manually selected AF point?". In my case it always tries to select a focus point at the center and I cannot get it to focus using one of the outer points.
In A+ I can get it to focus using the rightmost column of points at 1/250th and F5.0, if I switch to M and set 1/250th and F5.6 then I can get the fourth row from the right to focus. I tried using evaluative metering too instead of spot, but that doesn't change anything.
Strange

Cheers

First of all, having the camera in M, Av, Tv or even P mode has nothing to do with AF.  Those modes deal with exposures.  You can set the focus point with any of those modes.  Secondly, in A+ modes, you are letting the camera do all the decisions for you, both the exposure and what to focus on.  The AF cases wasn't designed for that style of shooting, if you call that a style at all.

For shooting birds in flight (or divers), I suggest to change your Selectable AF point to only cross-type.  That is located on the 4th section of the AF tab menu.  Just know that if you do this, the camera will only allow the cross-type points available for the attached lens and is normally dictated by the lens' maximum aperture.  With this selected, change the way the AI Servo works.  Go to the 2nd section of the AF tab.  Set the AI Servo 1st image priority to focus.  Set the AI Servo 2nd image priority to focus.  Now you can play with the "AF cases" if you want.  I personally leave it on Case 1.  I don't see any practical difference in any of those "Cases."

As for the red dot/focus point flashing,  this is irrelevant on AI servo mode.  If you want to see where you are focusing, you can set the AF point display during focus on 5th section of the AF tab to Selected (pre-AF, focused).

Remember, none of these will do you any good if you're shooting on the green mode.

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Re: My never ending Focus woes with my 5DMK3
« Reply #12 on: January 12, 2013, 11:49:48 AM »

East Wind Photography

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Re: My never ending Focus woes with my 5DMK3
« Reply #13 on: January 12, 2013, 11:54:47 AM »
Yep it you have a high contrast horizontal object in the background and an AF point is sensitive to that it will take priority over the low contrast vertical edge of the diver.  I either use spot AF or ALL AF points and lock using the center point initially and let the AF system track the edges for me.

I'll add it's still not 100% unless I use center point only and track on the swim shorts.

1DX does the same thing.  I shot a diving meet last night and zone AF, no matter which tracking case, couldn't lock on the diver all the way through.  It would focus on stupid things in the background every 3rd shot.  I was in extremely low light, however, and that no doubt contributed to this.

bjd

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Re: My never ending Focus woes with my 5DMK3
« Reply #14 on: January 12, 2013, 12:12:55 PM »
First of all, having the camera in M, Av, Tv or even P mode has nothing to do with AF.  Those modes deal with exposures.  You can set the focus point with any of those modes.  Secondly, in A+ modes, you are letting the camera do all the decisions for you, both the exposure and what to focus on.  The AF cases wasn't designed for that style of shooting, if you call that a style at all.
I know, and I dont use it, but, something works differently when it is set. And I wish I knew what setting causes that.
Remember, none of these will do you any good if you're shooting on the green mode.
True, but I am still intrigued why the outer column will do what I want in green mode,
but not when set to Av, Tv or M. Thats why I set the same parameters in M as were used in A+,
but it made no difference.
I have not selected any AF points, I let the camera do automatic selection.

Also I am using cars as they are a lot more predictable than birds. I though that if I could get it
to work with cars then I'll go back to birds after that and hone the settings.
Cheers Brian
« Last Edit: January 12, 2013, 12:22:20 PM by bjd »

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Re: My never ending Focus woes with my 5DMK3
« Reply #14 on: January 12, 2013, 12:12:55 PM »