Has back button autofocus outlived its usefulness?

[Pelu2010]

Advertisement (gone after registration)

I use it on the q3 28 to set the focus in an area where subjects pass by and the af would hunt between infinity and close focus. 

[Jeff S]

56 minutes ago, Pelu2010 said:

I use it on the q3 28 to set the focus in an area where subjects pass by and the af would hunt between infinity and close focus. 

I thought you complained about lack of proper BBF.  Was this changed?

 

[Ken Abrahams]

I use a mixture of BBF and normal shutter press for focus for different scenarios. I hate when the camera tracks and focusses on the wrong person, sometimes there is not enough time to use the toggle to select focus and then press shutter. Using Tracking Body/Face Detection with AFC on the SL3 and SL3S is very quick to snap on subjects. I have achieved critical focus on street subjects when spontaneous, last minute turns to grab focus on the fly would normally be a fail using the BBF. I cant press different buttons consecutively in these scenarios. On AFC using the shutter, the camera quickly changes focus on whatever direction you point it toward. If there is enough time it doesn't hurt to press once to grab the target and then shoot. Many times I have only pressed the shutter once (to expose) on such settings and the camera has achieved accurate focus. 

In static scenes with contrasty light I try using spot focus and the crosshairs otherwise one runs out of exposure compensation settings. There is less concern to check focus manually with this method. Not being able to explicitly trust focus peaking, requires such double checking with Multi field or Field methods. Of course, the Manual Focus setting allows for different combinations using Customise Control choices for the Joystick such as AF/AE lock or both and the choice of maintaining that lock by either holding the joystick or pressing it will only work when BBF is deselected. It's easy enough to hold the shutter down to hold the exposure lock when selecting specific areas for exposure control.

The BBF remains a very important tool for me when there are several people in a street scene and I shooting at 1.4. I haven't quite worked out what AF-On is all about, it came with the last Camera firmware? Perhaps this just another way of having dedicated BBF selection?   

  

[Luke_Miller]

I continue to use BBF since adding the SL/SL2/SL2-S to my Nikon Z8.  I have struggled to find common autofocus settings so that I don't have to remember which camera I have in hand.  I like being able to do a quick autofocus on a static subject using a focus point in the middle and then recomposing to get the framing I want.  The biggest challenge is that in AFC the Nikon will lock focus when I stop focusing while the SL bodies will often be in the middle of its focus-defocus cycle and be out of focus when I stop focusing.  AFS works fime, but that defeats the BBF concept of working for both static and moving subjects.

What works for me with both is AFC and tracking.  So with either a static or moving subject I am continuusly autofocusing.  Despite the poor reputation of SL AFC mode this works well even on moving subjects. 

Edited October 9 by Luke_Miller

[Jptsr1]

Stopped using it when I got my A7III and R6. Their version of subject tracking (which is what I use mostly even for stills) was good enough. When I added the Sl2 to my kit although the auto focus wasn't great I just never went back. I still shoot Canon, Sony and Fuji without it so it seems like it would be weird to use BBF with just one system. 

[LD_50]

On 4/24/2024 at 10:02 AM, Luke_Miller said:

I've used the back button autofocus technique for over 15 years with my DSLRs and now the SL bodies.  Currently I am set up in AF-C and Dynamic (Tracking) mode with autofocus on the joystick and that works well for me.  My SL2 appears to work well in face detect mode which appeals to me as an event shooter.  Unfortunately, by assigning autofocus to the joystick I lose the ability to change the face (or eye) being focused on if it is not the one I want.  Is it time to move on from back button autofocus?

It works great on other systems. Leica simply needs to add a way to switch faces/eyes/subjects while back button focus is being used. I’ve requested this and have not heard back. 

[LD_50]

Advertisement (gone after registration)

On 4/25/2024 at 10:29 AM, Luke_Miller said:

Yes, with my Nikon bodies there is an AF-On button that initiates autofocus. There is also a joystick that allows one the move the focus point or select a different face/eye (when in face detect) than the one the camera selected.  My problem with using face detect on my SL2 is that I have not found a way to change the camera selected face or eye if using the joystick to autofocus.

Nikon also allows the focus point joystick to be pressed to activate AF, through a custom setting. When that’s done, you can still select focus points with the joystick, unlike Leica’s current implementation, which seems like an oversight or bug. 

[SolarChronicle]

In my opinion, back-button focus was useful for “focus and recompose” shooters during the DSLR era, but with today’s mirrorless cameras offering excellent 3D tracking, it’s no longer necessary.

[BernardC]

13 hours ago, SolarChronicle said:

In my opinion, back-button focus was useful for “focus and recompose” shooters during the DSLR era, but with today’s mirrorless cameras offering excellent 3D tracking, it’s no longer necessary.

It depends on the use case. Tracking is better if you are tracking a subject, but BBF and magnification will be better for shots where precise positioning of the focus plane is important.

[Luke_Miller]

15 hours ago, SolarChronicle said:

In my opinion, back-button focus was useful for “focus and recompose” shooters during the DSLR era, but with today’s mirrorless cameras offering excellent 3D tracking, it’s no longer necessary.

Actually, I attribute my SL/SL2/SL2-S success with moving subjects to my use of BBF.  I have no difficulty getting in-focus shots of running children or children coming down a waterslide as long as I allow the autofocus system a moment to develop a track on the subject.  That is a technique I learned with my early Nikon autofocus cameras.  Due to the latency in the system, Nikon used "predictive autofocus" in which the camera needed a track on the moving subject so as to be able to predict where to mechanically place lens focus. That approach works equally well fo me with Leica's contrast detect autofocus.  BBF makes it easier for me to do that.

Edited October 14 by Luke_Miller

[SrMi]

On 10/14/2025 at 12:55 AM, SolarChronicle said:

In my opinion, back-button focus was useful for “focus and recompose” shooters during the DSLR era, but with today’s mirrorless cameras offering excellent 3D tracking, it’s no longer necessary.

I do not see a relation between "focus and recompose" and BBF. It is the same without BBF (half-press shutter).

BBF allows you to independently control focusing from taking the image. With BBF, you have instant access to AF-S, AF-C, and MF. Without BBF your camera refocuses every time you press the shutter even if you do not need to.

[SolarChronicle]

On 10/15/2025 at 9:02 AM, SrMi said:

I do not see a relation between "focus and recompose" and BBF. It is the same without BBF (half-press shutter).

BBF allows you to independently control focusing from taking the image. With BBF, you have instant access to AF-S, AF-C, and MF. Without BBF your camera refocuses every time you press the shutter even if you do not need to.

Yes. What I meant was that BBF made more sense for DSLR shooters who wanted the flexibility to capture both action and stills by keeping their camera in AF-C mode. They could track moving subjects, and when shooting something still, simply focus and recompose. But with modern cameras like the Z9 offering excellent 3D tracking, we can stay in AF-C  and skip BBF altogether.

[MikeZ]

I agree with Jptsr1. I've tried it on my R5 but couldn't get used to it and found that subject tracking did a fine job. I've not tried BBF on my SL3-S, but given my R5 experience I don't think that I'll take the leap.

[SrMi]

1 hour ago, SolarChronicle said:

Yes. What I meant was that BBF made more sense for DSLR shooters who wanted the flexibility to capture both action and stills by keeping their camera in AF-C mode. They could track moving subjects, and when shooting something still, simply focus and recompose. But with modern cameras like the Z9 offering excellent 3D tracking, we can stay in AF-C  and skip BBF altogether.

But what if you do not want to use AF-C with tracking, e.g., for landscape. Without BBF, you need to switch modes. When you are on a safari, you shoot both landscape and wildlife. Also, you do not need to focus and recompose with BBF as you can move the focus point and maintain precise focus (which you lose with focus and recompose). 

[SolarChronicle]

11 minutes ago, SrMi said:

But what if you do not want to use AF-C with tracking, e.g., for landscape. Without BBF, you need to switch modes. When you are on a safari, you shoot both landscape and wildlife. Also, you do not need to focus and recompose with BBF as you can move the focus point and maintain precise focus (which you lose with focus and recompose). 

When it comes to landscapes, I might still leave the camera in AF-C with 3D-tracking (on a Z9 or similar), focus on a tree, and then recompose. Same goes for handheld macros. But yeah, I totally get where you’re coming from. 

[jaapv]

On 10/16/2025 at 7:37 PM, SrMi said:

But what if you do not want to use AF-C with tracking, e.g., for landscape. Without BBF, you need to switch modes. When you are on a safari, you shoot both landscape and wildlife. Also, you do not need to focus and recompose with BBF as you can move the focus point and maintain precise focus (which you lose with focus and recompose). 

On Safari the landscape shots are made with a second or rather third camera in my experience. One for the long zoom, one for the medium zoom and one for the landscape lens.  No way am I going to change lenses in the dust-ridden outdoors. Just set it up as you wish. Anyway I prefer AFs ( or manual focus when static) for wildlife shots as I find control over critical focus essential, and it gets lost using AFc. AFc and Field is for BIF using a Dot Sight, not the viewfinder. 

[SrMi]

2 hours ago, jaapv said:

On Safari the landscape shots are made with a second or rather third camera in my experience. One for the long zoom, one for the medium zoom and one for the landscape lens.  No way am I going to change lenses in the dust-ridden outdoors. Just set it up as you wish. Anyway I prefer AFs ( or manual focus when static) for wildlife shots as I find control over critical focus essential, and it gets lost using AFc. AFc and Field is for BIF using a Dot Sight, not the viewfinder. 

Yes, multiple cameras with different lenses are best for dusty environment, though I do not believe there is such thing as a landscape lens. Any focal length can be a landscape lens.

With BBF you have AF-S (press and release), AF-C (press and hold) and MF (do not press) instantly accessible. That is the advantage of BBF, and shows that it has not outlived its usefulness.

[jaapv]

2 hours ago, SrMi said:

though I do not believe there is such thing as a landscape lens. Any focal length can be a landscape lens.

Precisely Reason I did not specify it. 

[V23]

On 4/25/2024 at 1:02 AM, Luke_Miller said:

I've used the back button autofocus technique for over 15 years with my DSLRs and now the SL bodies.  Currently I am set up in AF-C and Dynamic (Tracking) mode with autofocus on the joystick and that works well for me.  My SL2 appears to work well in face detect mode which appeals to me as an event shooter.  Unfortunately, by assigning autofocus to the joystick I lose the ability to change the face (or eye) being focused on if it is not the one I want.  Is it time to move on from back button autofocus?

Long live BBF!

[Advertisement]

Hallo,

Look here: Leica L-Mount

[matted]

On 10/7/2025 at 11:32 AM, Jeff S said:

I’ve used BBF on my SL2 since purchase years ago, coupled with focus ring turn for magnification if needed.  Comfort with the technique has given me pause for acquiring a Q3-43 for travel, since a different shooting workflow, with new muscle memory, would be needed.

I wonder how others using BBF on the SL  system have dealt with concurrent use of a Q.

Concurrent use of a Q2 and BBF on my SL2-S has never been an issue for me, as I don't seem to ever require use of continuous AF on the Q2... I am either in single AF mode for static subjects, or I pop it into manual to pre-focus or zone focus as needed. I appreciate that this probably wouldn't work as well with the 43mm focal length of the Q3-43 as it does with the 28mm of my Q2.

 

Regarding the initial question, unfortunately my SL2-S has developed an issue with the joystick (either from wear, or as a result of a bath it took last year) which has turned it into a toggle switch; once depressed to activate cAF, it does not deactivate AF when released. One must depress it once to activate AF, and depress it again to deactivate. Although it still sort of works as intended, it is not nearly as smooth and seamless switching back and forth between continuous and single AF as I am accustomed to doing which is a shame, and I have adapted to manually switching between focus modes using a function button as necessary.

 

I suppose if the subject tracking were as good as it is on modern Sony/Nikon/Canon systems and could stick with my chosen focus point in continuous AF even when the subject is static or when reframing, BBF would indeed no longer be required. Unfortunately the SL2-S cannot be trusted in this fashion and BBF is still king, at least for me.