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Author Topic: AF / AI Servo tips from 7D users  (Read 1859 times)

wickidwombat

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AF / AI Servo tips from 7D users
« on: March 28, 2012, 07:38:24 PM »
Just wondering if 7D users could give any specific AF / AI Servo tips for us with new 5Dmk3 since the AF system is so different than the previous 1D AF and the 5Dmk2 AF. Help us come up to speed quicker.
Since the 7D system is probably the closest AF system to the new system

currently I only use spot focus select point, I use back button focus,
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AF / AI Servo tips from 7D users
« on: March 28, 2012, 07:38:24 PM »

papa-razzi

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Re: AF / AI Servo tips from 7D users
« Reply #1 on: March 28, 2012, 08:18:06 PM »
For AI servo there are two basic types of settings -
1.  Setting a single focus point (or expanded focus point) and tracking the subject by keeping the focus point on the subject.  This is what I use most often.  It works well for soccer, track, and volleyball (that is what I shoot).  Basically, when you are trying to stay with one moving subject that is in a crowd of potential subjects - the camera wouldn't know what to focus on, so this one is best for that kind of shooting. 

2. Selecting a group of focus points and letting the camera track the subject within that grouping.  As the subject moves, the camera will switch focus points.  In this setting, you can select the starting focus point, and then the camera takes it from there.  If your subject is moving around but largely staying within the frame, this would work.  If the subject is fairly isolated this makes sense to use.  I don't use this one much.

There are a number of other settings in the custom settings for fine tuning how the AF system behaves.  For example, if the focus point loses the subject you can adjust how quickly will the camera focuses on something else.  For example, if you are tracking a bird in flight and lose the subject for a second, you can set the change to be slow so the camera will not focus quickly on something in the background while you are trying to get the subject back under a focus point.

It can get complicated with all the custom settings, but at the core of it, it is pretty simple as I described it above.  The 1D Mark IV manual is on the web and there is good detail on how that AF system works, which might also help.
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gmrza

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Re: AF / AI Servo tips from 7D users
« Reply #2 on: March 28, 2012, 08:23:51 PM »
I probably took longer than I should have to get used to using the M-fn button.  Assuming the way in which you control the selection of AF modes (or at least the groups of AF points) is the same in the 5DIII as on the 7D, getting used to the M-fn button is the biggest step to getting comfortable with the AF system, and changing between single-point, all points and groups of AF-points quickly.

"Press the M-fn button!"
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Jamesy

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Re: AF / AI Servo tips from 7D users
« Reply #3 on: March 28, 2012, 10:22:40 PM »
I use back button focus,
The AF-ON button is what you are referring to for back button focus. On my 40D I had the ability to change the behaviour of the shutter button/AF-ON button via the 'Shutter Button/AF-ON' Custom Function IV.

the options are explained here:
http://forums.dpreview.com/forums/read.asp?forum=1019&message=26913499

I am trying to find the same menu on my 5D3 and cannot.

Do any of you know where I can find it? Does it still exist? I like to be able, at times, to meter with the shutter button and focus with the AF-ON.

wickidwombat

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Re: AF / AI Servo tips from 7D users
« Reply #4 on: March 28, 2012, 10:25:37 PM »
I use back button focus,
The AF-ON button is what you are referring to for back button focus. On my 40D I had the ability to change the behaviour of the shutter button/AF-ON button via the 'Shutter Button/AF-ON' Custom Function IV.

the options are explained here:
http://forums.dpreview.com/forums/read.asp?forum=1019&message=26913499


I am trying to find the same menu on my 5D3 and cannot.

Do any of you know where I can find it? Does it still exist? I like to be able, at times, to meter with the shutter button and focus with the AF-ON.

C. Fn 2, Custom Controls, set the first option (shutter button) to either "Metering Start" or "AE Lock".
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Jamesy

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Re: AF / AI Servo tips from 7D users
« Reply #5 on: March 28, 2012, 10:38:45 PM »
C. Fn 2, Custom Controls, set the first option (shutter button) to either "Metering Start" or "AE Lock".
Thanks! I had just stumbled across it myself :-) It works just like before.

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Re: AF / AI Servo tips from 7D users
« Reply #5 on: March 28, 2012, 10:38:45 PM »