Can someone dumb down BBF back button focus for me?

[ilzho]

Ok, I am trying to understadn about back button focus, but I am not truly underatnding it.

Can someone dumb this down for me?

There are a lot of people who love it and I am not grasping the concept.

I have a 7d mark ii, shoot mostly in ai servo, burst mode, center point AF.

Thank you,

David 

[kvbarkley]

It is just a method of decoupling the focus function from the shutter button. It allows you to focus and then press the shutter any number of times without changing focus.

[TTMartin]

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@ilzho wrote:

Ok, I am trying to understadn about back button focus, but I am not truly underatnding it.

Can someone dumb this down for me?

There are a lot of people who love it and I am not grasping the concept.

I have a 7d mark ii, shoot mostly in ai servo, burst mode, center point AF.

Thank you,

David 

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Back Button Focus is having to press two buttons instead of one.

You camera normally defaults so that AF and metering starts when you half press the shutter, and the shutter activates when you fully press the shutter.

Back Button Focus requires you to press a button on the back of the camera to activate focus (and removes it from the shutter button), and then press the shutter button to activate the shutter.

For AIServo and tracking moving subjects I would advise you do NOT use Back Button Focus.

The advantage of Back Button Focus is that you can suspend AF by releasing the rear button. The disadvantage of BBF is you have to press two buttons most of the time in order to be able to occasionally suspend focus.

Instead all non-Rebel dSLRs since at least the 40D have an AF ON button on the back. This can be reprogrammed to AF OFF.

By doing this you can suspend AF by pressing the now AF-OFF button. This means that you only have to press two buttons occasionally when you want to suspend focus, instead of most of the time with BBF.

[ilzho]

Ok, this helps

I have no problem pressing the shutter button half way to achieve focus, although I still have lots to learn.

Thank you,

David

[Waddizzle]

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@ilzho wrote:

Ok, this helps

I have no problem pressing the shutter button half way to achieve focus, although I still have lots to learn.

Thank you,

David

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To each his own, I guess.  I like BBF, most especially in AI Servo mode.  Why?  I have a couple of reasons. 

Because I am not good at half depressing the shutter.without activating the shutter, or losing focus lock.  Picking out a bird on tree limb in the middle of a tree is much easier when you can press the shutter and not have the camera refocus, dropping focus on the bird.  Holding the BBF button is as natural as holding the camera, for me.  I have found it most useful with lenses that allow for MF override, because I can switch between MF and AF on the fly.

http://www.learn.usa.canon.com/resources/articles/2011/backbutton_af_article.shtml

Like i said, to each his own.  I suggest you give it a try, and see if you like it.  As noted above, the default behavior is that the camera engages AF when the shutter is half depressed.  BBF separates engaging AF to a separate button.  You will also have to remove AF from the shutter button, too.

[TTMartin]

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Waddizzle wrote:

 Picking out a bird on tree limb in the middle of a tree is much easier when you can press the shutter and not have the camera refocus, dropping focus on the bird.  Holding the BBF button is as natural as holding the camera, for me.  I have found it most useful with lenses that allow for MF override, because I can switch between MF and AF on the fly.

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All of that can also be done by pressing the AF-OFF button when needed.

I find the times I need to suspend focus, like those you mentioned above, occur a lot less than times that I want continuous focus. 

So for me, I would rather press two buttons sometimes, rather than two buttons most of the time. 

[Waddizzle]

"All of that can also be done by pressing the AF-OFF button when needed."

If you mean holding the AF-OFF button, so that you can manually override the AF and turn the focus ring just seems more complicated to me.  Pressing the shutter becomes a third task: focus ring, AF-OFF, and shutter.

Like I said, to each his own.  If I want to manual focus, I simply tap BBF, turn the focus ring, and press the shutter when I want.  I can hold the shutter button half-depressed to keep MF Override engaged.  If I want AF, I just hold the BBF button for AI Servo mode, or tap it briefly for "One Shot", even if the camera is in AI Servo Mode.

I don't think there is no one right way to always use the camera.

[Waddizzle]

"Because I am not good at half depressing the shutter.without activating the shutter, or losing focus lock."

Holding the shutter is easy.  Holding the shutter while the camera is moving is not.  Holdng and moving is hard for me.

[ilzho]

Well I will give it a try, eventually.....

Thanks

[ebiggs1]

It is one of those things where if you need it, it is great.  If you don't it's useless.  Most of the time it is useless if all you shoot is the run of the mill things.  It can even hurt in some situations.  I rarely to never make use of it.