Back Button Focus


Apr 1, 2002
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#1
Hi people,

just curious how many of you uses the back button auto focus instead of the half shutter autofocus?

cheers!
 

RhysCheng

New Member
Feb 4, 2011
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#2
i do. hence my camera is always in continuous focusing. this is because im primarily shooting sports and events so no hassle in changing modes.
 

Rashkae

Senior Member
Nov 28, 2005
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#3
I only use it to reselect the center AF point.
 

Mar 14, 2013
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#4
i use it when i need to ensure that focus is perfect(after using BBF, then enlarging the point and using manual to adjust)
 

daredevil123

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Staff member
Oct 25, 2005
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lil red dot
#5
Using AF-C together with AF-On is a very useful technique. AF-C is great for keeping subjects in focus even if they move, but in certain instances, where you want to place the subject outside of any selectable focus points, or when you have very little time to switch the AF points, the use of AF-On together with AF-C can be very useful. So pretty much this method will still give you the ability to focus and recompose and still have AF-C handy when you need it.

The only issue is to get used to working this way, that the shutter release and the focus acquisition is de-coupled.

BTW, this is used a lot by many wedding photographers, especially those who shoot with primes and ambient light. I use it from time to time in my work too.
 

sjackal

Senior Member
Jul 9, 2008
4,490
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#7
Once you do, you never look back.

It enables you to immediately and effectively diffuse the "You got a nice camera" misconception.

"Bro your pictures very nice, your camera must be damn nice and expensive."

"Yeah, come help me take some pics too" - turns manual focus ring, pass the camera to the guy, click click click.

"Bro, my camera nice, but pictures you take all blur one leh!"
 

Mustank

New Member
Aug 10, 2008
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#8
Donno whether got people invent something that can clip on a small boy
Then the camera use radio frequency to track the boy running
Then the camera just ownself auto focus based on the distance
Like that even got other children come in between the boy and camera, the camera also can focus on the correct boy
 

Rashkae

Senior Member
Nov 28, 2005
19,105
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#9
Donno whether got people invent something that can clip on a small boy
Then the camera use radio frequency to track the boy running
Then the camera just ownself auto focus based on the distance
Like that even got other children come in between the boy and camera, the camera also can focus on the correct boy
Sony uses registered face recognition and tracking AF for that. No need for a clip.
 

TWmilkteaTW

Senior Member
May 30, 2011
2,251
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#10
Using AF-C together with AF-On is a very useful technique. AF-C is great for keeping subjects in focus even if they move, but in certain instances, where you want to place the subject outside of any selectable focus points, or when you have very little time to switch the AF points, the use of AF-On together with AF-C can be very useful. So pretty much this method will still give you the ability to focus and recompose and still have AF-C handy when you need it.

The only issue is to get used to working this way, that the shutter release and the focus acquisition is de-coupled.

BTW, this is used a lot by many wedding photographers, especially those who shoot with primes and ambient light. I use it from time to time in my work too.
Happen to read about this BBF thing and AF-on method over the internet. Did a search and found this thread..(Sorry to dig this up)

But assuming i didnt do this settings to my camera... Currently on AF-C mode and have no time to change to AF-S or switch the AF points..
Wouldn't using the focus hold/focus lock button the lens works too?

Example. Half-press the shutter button to get focus while in AF-C..follows by pressing down the focus hold button on the lens barrel then recompose and fire off.
 

thoongeng

Senior Member
Jan 26, 2010
1,246
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#11
Happen to read about this BBF thing and AF-on method over the internet. Did a search and found this thread..(Sorry to dig this up)

But assuming i didnt do this settings to my camera... Currently on AF-C mode and have no time to change to AF-S or switch the AF points..
Wouldn't using the focus hold/focus lock button the lens works too?

Example. Half-press the shutter button to get focus while in AF-C..follows by pressing down the focus hold button on the lens barrel then recompose and fire off.
Your idea is workable too...

Though I think the main use of back button focus with continuous autofocusing is using the AF-ON button as the 'immediate' on-off buttton for AF (and the shutter release only controls shutter release and metering). Hold it track focus, or just press it briefly to focus lock (like using AF-S / one-shot AF without changing the AF mode).

Another thing is that many lenses or camera bodies may not have focus hold button (unless you switch to manual focus)... but I think many entry level DSLRs can reprogramme their AEL/AFL button to do AF-ON duty :)
 

Last edited:

vivakid

New Member
Jul 21, 2012
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#12
Hi all,

Have recently learnt about BBF and it has been pretty useful. Jus a question which I hope CSers would be able to advise on.

To use bbf, meter, recompose and take a shot on a tripod how should one do it? Canon Shooter and I'm using only center AF point. I typically shoot AV.

1.So first, with cam on tripod but not tighten, I'll bbf on the object with center AF.

2.Then meter (could be different from focused object) with half press shutter also with center AF.

3.Recompose my shot, still holding shutter half pressed.

4.After recompose, tighten tripod, still half pressing shutter.

5.Once tripod tighten, finally then taking the shot.

There's so many steps, would there be a more finesse way? Many thanks in advance!!
 

thoongeng

Senior Member
Jan 26, 2010
1,246
15
38
#13
Hi all,

Have recently learnt about BBF and it has been pretty useful. Jus a question which I hope CSers would be able to advise on.

To use bbf, meter, recompose and take a shot on a tripod how should one do it? Canon Shooter and I'm using only center AF point. I typically shoot AV.

1.So first, with cam on tripod but not tighten, I'll bbf on the object with center AF.

2.Then meter (could be different from focused object) with half press shutter also with center AF.

3.Recompose my shot, still holding shutter half pressed.

4.After recompose, tighten tripod, still half pressing shutter.

5.Once tripod tighten, finally then taking the shot.

There's so many steps, would there be a more finesse way? Many thanks in advance!!
Sounds like it will be easier to use Manual exposure mode... focus and meter first then you have all the time to set it up on tripod.
Unless you use autoexposure-lock and set up the camera quickly before the set time for AEL expires :)
 

Turbonetics

Senior Member
Feb 19, 2009
2,701
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#14
Does AF-ON button works the same as half pressed shutter button?
 

Jun 7, 2011
939
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#15
Does AF-ON button works the same as half pressed shutter button?
Usually shutter release button will AF & meter, and then trigger the shutter.

I might be wrong, but depending on the camera settings, I think you can customize your AF-on button to either just AF, meter, or both AF & meter.
 

Turbonetics

Senior Member
Feb 19, 2009
2,701
6
38
#16
Usually shutter release button will AF & meter, and then trigger the shutter.

I might be wrong, but depending on the camera settings, I think you can customize your AF-on button to either just AF, meter, or both AF & meter.

i see..
but if i use Manual settings to adjust my own exposure,does it make a difference to use either of these button assuming my shutter button is default to metering and AF?
 

Jun 7, 2011
939
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#17
i see..
but if i use Manual settings to adjust my own exposure,does it make a difference to use either of these button assuming my shutter button is default to metering and AF?
On my camera body, if i set my back button only to meter and the exposures are all manual (shutter, iso, aperture), it seems like it does nothing.

Probably some other camera bodies will still start metering only to inform you that it's underexposed / overexposed through the viewfinder or LCD.. ( but I think nowadays it's all automatic? CMIIW :) )
 

Turbonetics

Senior Member
Feb 19, 2009
2,701
6
38
#18
On my camera body, if i set my back button only to meter and the exposures are all manual (shutter, iso, aperture), it seems like it does nothing. Probably some other camera bodies will still start metering only to inform you that it's underexposed / overexposed through the viewfinder or LCD.. ( but I think nowadays it's all automatic? CMIIW :) )
I just read an article write up on this.
It does seems pretty similar to the half pressed shutter functions. Iam still more used to the traditional shutter half pressed.
My BBF button was set at certain aperture and shutter speed and still can track focus..I use it mainly for bird in flight shots when I don't have to readjust my settings to save much time.
 

coolhand57

New Member
Apr 14, 2012
289
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Singapore
#19
My BBF button was set at certain aperture and shutter speed and still can track focus..I use it mainly for bird in flight shots when I don't have to readjust my settings to save much time.
I never knew AF ON button can set certain aperture and shutter speed. i know it just works like half button pressed, giving you the flexibility to activate metering and change settings necessary to changing light situation without changing focus if the subject remains stationary or no need to refocus.
 

daredevil123

Moderator
Staff member
Oct 25, 2005
21,645
63
48
lil red dot
#20
I never knew AF ON button can set certain aperture and shutter speed. i know it just works like half button pressed, giving you the flexibility to activate metering and change settings necessary to changing light situation without changing focus if the subject remains stationary or no need to refocus.
On some camera models that button can be reassigned.
 

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