# Question about Back Button Focus



## assassin11 (Sep 13, 2015)

I recently started using back button focus and I have a question. Is it not possible to select a different focus point when using the back button focus technique? 

I was taking portraits of my niece so I selected a point closest to her eye but when I focus the camera still uses the centre point to set focus (the points closest to her eyes blinks, but does not focus). The only way to get focus on her eyes was to focus and then recompose.


I was using a Canon Mark III with a 24-70mm F4 lens.


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## mukul (Sep 13, 2015)

Hi,
This does not happen with my 600D. I can focus selected Focus Point using back button focus as long as it is beyond MFD.

5D3 users can give you exact settings option.
Also you should consult the camera manual and google how to do Back Button Focus on 5D3


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## coldsweat (Sep 13, 2015)

My 5D3 uses the selected focus point while using BBF - the following should fix the problem for you hopefully.

There is a setting under 'C.Fn2 / Custom Controls / AF-ON button / Metering and AF start / Detail Set (press the info button) that gives you the option of 'Manually selected AF point' & 'Registered AF point' that may well be it (you obviously need it set to 'Manually selected AF point')!


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## Tinky (Sep 13, 2015)

Can I ask a broader question?

I've used my SLRs the same way since forever, I've often scrolled past the back button focus option in custom functions, but never really bothered with it, not fully understanding the need for it, or potential benefits...

Could some users 'sell' it to me?

Many thanks


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## candc (Sep 13, 2015)

good for focus and recompose using ai servo and you want the camera to stop af (just release bbf button) the key is to take af off of the shutter release button. 

i like it on the 7dii because you can set 2 different focus modes to adjacent buttons ie: main button is large zone, ai servo, high speed cont. adjacent button is center point single, single shot af, one shot drive.


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## Orangutan (Sep 13, 2015)

Tinky said:


> I've used my SLRs the same way since forever...not fully understanding the need for it, or potential benefits...



Me too, though I've played with it a little. My understanding is that it lets you separate metering and focus. So far that hasn't been a big deal for me, but good photographers tell me I need only have more faith keep working with it, and I'll become enlightened.

I, too, would like to be convinced.


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## privatebydesign (Sep 13, 2015)

Orangutan said:


> Tinky said:
> 
> 
> > I've used my SLRs the same way since forever...not fully understanding the need for it, or potential benefits...
> ...



I tried BBF, hated it, missed loads of shots and lots of shots were not in focus, user error to be sure but I didn't get on with it. 

However I did see the utility in being able to separate focus from metering, being able to switch AF off for a fraction of a second when something that would distract it came in to frame etc, so after looking through the various options I tried BBFocus Off. This, to me, is far more intuitive, I don't get thumb fatigue and most of the time I want metering I also want focus, but I can now split the two.


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## Click (Sep 13, 2015)

That's a very good option, privatebydesign. I'll try it.


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## assassin11 (Sep 13, 2015)

coldsweat said:


> My 5D3 uses the selected focus point while using BBF - the following should fix the problem for you hopefully.
> 
> There is a setting under 'C.Fn2 / Custom Controls / AF-ON button / Metering and AF start / Detail Set (press the info button) that gives you the option of 'Manually selected AF point' & 'Registered AF point' that may well be it (you obviously need it set to 'Manually selected AF point')!



Thank you for this coldsweat, it worked like a charm! 

Thanks everyone for the replies.


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## unfocused (Sep 13, 2015)

Tinky said:


> Can I ask a broader question?
> 
> I've used my SLRs the same way since forever, I've often scrolled past the back button focus option in custom functions, but never really bothered with it, not fully understanding the need for it, or potential benefits...
> 
> ...



The main advantage of back button autofocus is to separate shutter release from focusing. Many people (myself included) like being able to separately control autofocus and shutter release. I can keep the shutter button half-pressed with one finger, while using my thumb to focus (by pressing the AF-On button). It's very easy to train yourself to do this.

That way, if I need to stop focusing to recompose, I don't have to worry about the camera refocusing when I press the shutter button. Or, if I am following action and something or someone comes into the frame that might cause the camera to change focus, I can simply take my finger off the focus button and it will keep focus on the original subject. 

It's a matter of personal preference and I'd recommend people try it for a few days and see if it is for them or not.


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## Kestrel (Sep 13, 2015)

I like to use back button focusing mainly for birding. Often I have a single focus point set so that I get focus on the birds eye, then recompose for composition before taking the shot. It's handy when there are also other elements in the scene (branches, leaves, etc) that the autofocus might "grab" onto if left to its own devices. I keep one of the custom function settings on the 5D III set for back button focusing, so that I can use it when it is appropriate.


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## drmikeinpdx (Sep 14, 2015)

I switched to back button focus on my 5D3 a couple of years ago. I mostly shoot people who are holding fairly still - or at least not changing their distance from the camera. I always choose a single focus point that is close to where it needs to be, but it is rarely exactly where I want it.

If I use shutter button focus, I put the selected focus point on a person's eye, then hold the shutter button halfway down, then recompose before taking the shot. But here's why I switched:

Most of the time, I'm taking 5-20 shots of a particular pose in order to catch different facial expressions. If I have to focus and recompose each time, it is annoying and really slows things down.

With back button focus, I focus once, then leave the focus button alone until the scene changes and I need to focus again. It's a much faster system for my type of shooting.

If you are shooting moving targets or only take one shot of each subject, then shutter button focus might be better for you.

I keep my Rebel-class bodies set for shutter button focus since I use them for travel and street photography. I mostly use the center focus point and recompose. My large bodies are used for posed/portrait/studio/boudoir type work, so they are set for back button focus.


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## StudentOfLight (Sep 14, 2015)

I find it particularly useful when tracking wildlife and birds. e.g. When panning, if there are obstructions that come between you and the subject then you lift off back button and can keep the subject relatively in focus. When it emerges from the trees you can resume BBF and the camera will lock focus more easily. There are some AF settings that you can tweak to ignore obstructions but i find it less predictable than lifting off, especially if you are intending to shoot subjects that move erratically. 

By that I mean if i'm intending to go out and shoot erratic subjects like small birds, I set my camera up to best shoot erratic subjects. The exceptional case (if an object comes between me and subject) I'd prefer to manage myself.


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## privatebydesign (Sep 14, 2015)

StudentOfLight said:


> I find it particularly useful when tracking wildlife and birds. e.g. When panning, if there are obstructions that come between you and the subject then you lift off back button and can keep the subject relatively in focus. When it emerges from the trees you can resume BBF and the camera will lock focus more easily. There are some AF settings that you can tweak to ignore obstructions but i find it less predictable than lifting off, especially if you are intending to shoot subjects that move erratically.



And that is exactly why I find BBF Off mode far more intuitive. I want focus on more often than not, so using a second digit to enable it all the time makes no sense to me, yet using one on the occasions I don't want it on does.


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## East Wind Photography (Sep 14, 2015)

StudentOfLight said:


> I find it particularly useful when tracking wildlife and birds. e.g. When panning, if there are obstructions that come between you and the subject then you lift off back button and can keep the subject relatively in focus. When it emerges from the trees you can resume BBF and the camera will lock focus more easily. There are some AF settings that you can tweak to ignore obstructions but i find it less predictable than lifting off, especially if you are intending to shoot subjects that move erratically.
> 
> By that I mean if i'm intending to go out and shoot erratic subjects like small birds, I set my camera up to best shoot erratic subjects. The exceptional case (if an object comes between me and subject) I'd prefer to manage myself.



I concur. It took a while to get used to it. However the biggest benefit I get from bbf on is that I generally have more control with pretty much full time manual focus. Press the back button to AF and then can release to tweak or stick pick manually when AF fails to lock. I shoot a wide variety of subjects and find detaching AF from the shutter button much more useful than simple BBF off.


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## cervantes (Sep 14, 2015)

I wrote an extensive article about the 5D3 AF system that also deals with back button focusing. Check it out here:
http://www.focrates.com/articles/configuring_your_5d_mark_3_af_for_fast_action/configuring_your_5d_mark_3_af_for_fast_action.html


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## romanr74 (Sep 14, 2015)

I think it is of tremendous value when you are dealing with stacked subjects which also move or where you move. For instance when you shoot a group of people from the side and want slective sharpness. Or when you shoot through something, for instance foilage. Using BBF the triggering of the shutter doesn't f-up your focus distance, which is kind of hard to control otherwise unless you focus manuall which can have its downsides too.


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