Is anyone experience "back button focus" issue like this?

Started 3 months ago | Questions
WayneDST
WayneDST Forum Member • Posts: 52
Is anyone experience "back button focus" issue like this?

Recently I update my xt3 to fw4.0. the problem is

When I use AE-L/AF-L button as AF (back button focus as AF-on), and hold the button. Then I press the shutter button, the problem is sometimes it will trigger the re-focus action. It is quite annoying and missing focus point if I make a re-composition.

Does anyone experience this kind of issue? Is it a fw problem? Thanks.

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michaeladawson Forum Pro • Posts: 14,890
Re: Is anyone experience "back button focus" issue like this?

WayneDST wrote:

Recently I update my xt3 to fw4.0. the problem is

When I use AE-L/AF-L button as AF (back button focus as AF-on), and hold the button. Then I press the shutter button, the problem is sometimes it will trigger the re-focus action. It is quite annoying and missing focus point if I make a re-composition.

Does anyone experience this kind of issue? Is it a fw problem? Thanks.

Not sure but it sounds like one of your settings got changed, maybe due to the firmware upgrade.  There is a setting to disable AF on the shutter button.  I don't know what the setting is, but it's there.

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Mike Dawson

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Erik Baumgartner Senior Member • Posts: 3,212
Re: Is anyone experience "back button focus" issue like this?

WayneDST wrote:

Recently I update my xt3 to fw4.0. the problem is

When I use AE-L/AF-L button as AF, and hold the button. Then I press the shutter button, the problem is sometimes it will trigger the re-focus action. It is quite annoying and missing focus point if I make a re-composition.

Does anyone experience this kind of issue? Is it a fw problem? Thanks.

If you've decoupled AF from the shutter button, it shouldn't. Are you sure you're not just seeing the lens stop down when you half-press the shutter button? See if it still does anything with the lens wide open or in AF-C (which always operates at shooting aperture).

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Greybeard2017
Greybeard2017 Senior Member • Posts: 1,684
Re: Is anyone experience "back button focus" issue like this?
2

michaeladawson wrote:

WayneDST wrote:

Recently I update my xt3 to fw4.0. the problem is

When I use AE-L/AF-L button as AF (back button focus as AF-on), and hold the button. Then I press the shutter button, the problem is sometimes it will trigger the re-focus action. It is quite annoying and missing focus point if I make a re-composition.

Does anyone experience this kind of issue? Is it a fw problem? Thanks.

Not sure but it sounds like one of your settings got changed, maybe due to the firmware upgrade. There is a setting to disable AF on the shutter button. I don't know what the setting is, but it's there.

http://fujifilm-dsc.com/en/manual/x-t3/menu_setup/button-dial_setting/index.html#shutter_af

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WayneDST
OP WayneDST Forum Member • Posts: 52
Re: Is anyone experience "back button focus" issue like this?

Thanks for the input! Let me explain more about my case,

I didn't change the halfway shutter AE or AF function to off. I only set the function key - by setting the AE-L button as AF-on. As my thought, the shutter halfway pressed AF should be automatically off. However, my feeling is that the halfway AF is around 90% off. Another 10%, AF will be trigger by halfway pressed the shutter button. (I can hear the noise made by the AF motor)

I know it's not standard way to do auto focus. However it's good for using center af point to do the AF, then re-conposition, and then halfway press shutter button to do AE for final composition. (Moving af point by joystick takes more time.)

Set af-on on the AE-L button

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doak Regular Member • Posts: 192
Re: Is anyone experience "back button focus" issue like this?
5

Shutter AF is not automatically turned off when one of the back buttons is set to AF-ON.

See the link to the Fuji manual in the post immediately above your last.

You need to disable shutter AF for AF-S and/or AF-C.

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Erik Baumgartner Senior Member • Posts: 3,212
Re: Is anyone experience "back button focus" issue like this?
3

WayneDST wrote:

Thanks for the input! Let me explain more about my case,

I didn't change the halfway shutter AE or AF function to off. I only set the function key - by setting the AE-L button as AF-on. As my thought, the shutter halfway pressed AF should be automatically off. However, my feeling is that the halfway AF is around 90% off. Another 10%, AF will be trigger by halfway pressed the shutter button. (I can hear the noise made by the AF motor)

I know it's not standard way to do auto focus. However it's good for using center af point to do the AF, then re-conposition, and then halfway press shutter button to do AE for final composition. (Moving af point by joystick takes more time.)

You also have to disable AF for the shutter button.

http://fujifilm-dsc.com/en/manual/x-t3/menu_setup/button-dial_setting/index.html#shutter_af

Personally, I’ve found that Fujis don't work especially well with BBF and only use it (assigned to the rear command dial) in MF mode. I get far better results using the shutter button (X-T2/X-T20/X100V).

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WayneDST
OP WayneDST Forum Member • Posts: 52
Re: Is anyone experience "back button focus" issue like this?

Erik, thanks for reminding. I am pretty sure it's not AF-C.  I am using AF-S or M mode. Just trying which mode is more convenient for combining with AF-on.

Maybe it's not an issue. let me try more to confirm if there is really a problem.

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WayneDST
OP WayneDST Forum Member • Posts: 52
Re: Is anyone experience "back button focus" issue like this?
2

Doak, yes, you are right. The manual says I have to disable the AF. That's interesting, I will try more combination about these setting. Thanks.

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WayneDST
OP WayneDST Forum Member • Posts: 52
Re: Is anyone experience "back button focus" issue like this?

Hi Erik, I have tried BBF with MF mode. It works fine. What do you mean it doesnt work?

There is one issue I observed, when I set BBF+MF mode. When I hold the BBF buttoj, the AF+MF overwrite willnot works. I mean you cna't use the focus ring to change the focal distance. It eill be locked.

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Greybeard2017
Greybeard2017 Senior Member • Posts: 1,684
Re: Is anyone experience "back button focus" issue like this?
2

WayneDST wrote:

Hi Erik, I have tried BBF with MF mode. It works fine. What do you mean it doesnt work?

He said the opposite

There is one issue I observed, when I set BBF+MF mode. When I hold the BBF buttoj, the AF+MF overwrite willnot works. I mean you cna't use the focus ring to change the focal distance. It eill be locked.

Take your finger off the AF-ON or AF-L button and turn the focus ring.

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Ulrik Christiansen
Ulrik Christiansen Senior Member • Posts: 1,693
Re: Is anyone experience "back button focus" issue like this?

WayneDST wrote:

Recently I update my xt3 to fw4.0. the problem is

When I use AE-L/AF-L button as AF (back button focus as AF-on), and hold the button. Then I press the shutter button, the problem is sometimes it will trigger the re-focus action. It is quite annoying and missing focus point if I make a re-composition.

Does anyone experience this kind of issue? Is it a fw problem? Thanks.

Yes I have the same problem. I created a post on this topic, but nobody responded. I'll explain my experience here:

I have just bought myself a new x-t3 and installed the new firmware. While shooting some portraits in low light in manual focus (back-button) mode with the 56mm f1.2, I noticed that the focus jumps. Specifically, I press the AF backbutton to focus on an eye, I release it, and then when I press the shutter, the focus changes to around 2cm further back. The shutter AF is of course set to off.

I saw a comment in one of Omar Gonzales' videos where a user had the same problem with the same camera setup. He had already submitted the issue to Fuji support, which in turn had sent it to Fuji Japan, so he was sure that the issue will be fixed soon.

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Erik Baumgartner Senior Member • Posts: 3,212
Re: Is anyone experience "back button focus" issue like this?
6

WayneDST wrote:

Hi Erik, I have tried BBF with MF mode. It works fine. What do you mean it doesnt work?

There is one issue I observed, when I set BBF+MF mode. When I hold the BBF buttoj, the AF+MF overwrite willnot works. I mean you cna't use the focus ring to change the focal distance. It eill be locked.

BBF is just for momentary use in MF mode, often followed by fine tuning with the ring with magnified Focus Check on.

I wrote a thing about my experience with Fuji BBF a while ago and saved it. It also describes AF-C settings and other possibly useful tidbits you might find helpful so I’m just gonna save some time and paste it. ...

BBF (Back Button Focus) is usually used to decouple the AF function from the shutter button so you can continuously maintain AF on a moving subject independently with your thumb and shoot with your index finger on the shutter button, or focus on a static subject with a momentary touch of your thumb and then you recompose and shoot without the shutter button reinitiating AF. You can set your Fuji up this way too - I did, and while it works, it doesn’t work all that well. The Fuji AF-C (at least on the X-Trans III models - X-T2, X-T20, X-H1 etc) works FAR better when it first initilizes and locks on - if you use continuous BBF or engage AF-C using the shutter button using a half-press (with AF not decoupled from the shutter button), the AF system seems to get lazy, less responsive, and less accurate. I get far better results (with Boost mode and Focus Priority switched on) just following the subject with the focus box (usually single point, but occasionally zone) prepositioned where I want my subject to appear in the frame and fully mashing the shutter button down - no half press and track first (an initial quick half-press is a good idea to get a slow lens in the ballpark, though). I get tack sharp results nearly every time with this method with the 16-55, 50-140 and even using the slowpoke 35 and 56 lenses (though they can be slower to track initially.

Also, unlike AF-S, AF-C works at shooting aperture only, so you'll definitely want a larger aperture (f/2 - f/2.8 minimum in very low light). ...and don't use the smallest focus box (Single Point) for AF-C ever, it just doesn't work well, the dimmer the light, the bigger the focus box needs to be. The zone box seems to be the way to go for distant and/or isolated subjects like birds in flight (or maybe race cars etc.), but I find that single point tends to lock on a closer subject where I want it to, while zone will miss the target and pick a peripheral feature instead (or the wrong feature on the subject),YMMV.

For the fastest, most responsive AF try custom AF-C setting #6: Tracking Sensitivity: 0, Speed Tracking Sensitivity: 2, Zone Area Switching: FRONT (CENTER might work better if the subject isn’t coming right at you). I find that of the factory presets, #4 has the snappiest response time - I use it with my X-T20 which doesn’t have a mode #6 option. This also works very well in continuous shooting mode - I recommend CL mode, 5 fps or less unless you have lots of light and a contrasty subject. Use a slower speed with slower, older lenses. Again, YMMV. I do have BBF set up to work in M mode so I can easily focus, recompose and shoot with static subjects. In S mode I use the shutter button half-press and recompose method (with release priority). It sounds complicated, but it’s super simple once you get your head around it.

So with just moving the front AF switch, I get:

M mode - either manual focus or BBF single point (focus is automatically decoupled from the shutter button in M mode)

C mode - fast, accurate focus for moving subjects with a full press of the shutter button, or continuous tracking with a half-press (which can work quite well in some situations if you switch to Wide Tracking AF).

S mode - full button press if the focus box is on the subject, or half-press and recompose if it isn’t.

Lots of options for almost any situation just by rotating the little front switch (which can be done easily on the fly as the moment requires with your eye in the EVF). I use this on my X-T2 and X-T20 but it should be adaptable to any of the X-Trans III or IV cameras (although the newest cameras MIGHT work better with the DSLR method of continuous tracking). I use the rear command dial for AF On, and the AFL button for Focus Check, I hope some of that makes sense.

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WayneDST
OP WayneDST Forum Member • Posts: 52
Re: Is anyone experience "back button focus" issue like this?
1

Hi Ulrik, yes, that's what I experiencd.

I am using 56.2 too. Maybe this combination will cause the issue. Here is a video I made. You can see the first few second, M mode, when I press the shutter button. You can easily see the focus jump few cm.

At the same time, I can hear there is a sound, kind of motor rotating. But it sounds different as the sound during auto focusing.

Here is the video. I did few times of BBF test,  the first time has issue.

https://drive.google.com/file/d/1CEpgbOS3-W_2gR3ZRB8rkinAgXVRZrPZ/view?usp=drivesdk

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Ulrik Christiansen
Ulrik Christiansen Senior Member • Posts: 1,693
Re: Is anyone experience "back button focus" issue like this?

WayneDST wrote:

Hi Ulrik, yes, that's what I experiencd.

I am using 56.2 too. Maybe this combination will cause the issue. Here is a video I made. You can see the first few second, M mode, when I press the shutter button. You can easily see the focus jump few cm.

At the same time, I can hear there is a sound, kind of motor rotating. But it sounds different as the sound during auto focusing.

Here is the video. I did few times of BBF test, the first time has issue.

https://drive.google.com/file/d/1CEpgbOS3-W_2gR3ZRB8rkinAgXVRZrPZ/view?usp=drivesdk

Yes, exactly the same behavior with my x-t3 56 setup. But works fine with my x-t20.

I hope they will fix it, since I had gotten used to shooting this way with bbf and manual. Lets see.

The other user I talked with also experienced this with other lenses than the 56.

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WayneDST
OP WayneDST Forum Member • Posts: 52
Re: Is anyone experience "back button focus" issue like this?

Erik Baumgartner wrote:

WayneDST wrote:

Hi Erik, I have tried BBF with MF mode. It works fine. What do you mean it doesnt work?

There is one issue I observed, when I set BBF+MF mode. When I hold the BBF buttoj, the AF+MF overwrite willnot works. I mean you cna't use the focus ring to change the focal distance. It eill be locked.

BBF is just for momentary use in MF mode, often followed by fine tuning with the ring with magnified Focus Check on.

I wrote a thing about my experience with Fuji BBF a while ago and saved it. It also describes AF-C settings and other possibly useful tidbits you might find helpful so I’m just gonna save some time and paste it. ...

BBF (Back Button Focus) is usually used to decouple the AF function from the shutter button so you can continuously maintain AF on a moving subject independently with your thumb and shoot with your index finger on the shutter button, or focus on a static subject with a momentary touch of your thumb and then you recompose and shoot without the shutter button reinitiating AF. You can set your Fuji up this way too - I did, and while it works, it doesn’t work all that well. The Fuji AF-C (at least on the X-Trans III models - X-T2, X-T20, X-H1 etc) works FAR better when it first initilizes and locks on - if you use continuous BBF or engage AF-C using the shutter button using a half-press (with AF not decoupled from the shutter button), the AF system seems to get lazy, less responsive, and less accurate. I get far better results (with Boost mode and Focus Priority switched on) just following the subject with the focus box (usually single point, but occasionally zone) prepositioned where I want my subject to appear in the frame and fully mashing the shutter button down - no half press and track first (an initial quick half-press is a good idea to get a slow lens in the ballpark, though). I get tack sharp results nearly every time with this method with the 16-55, 50-140 and even using the slowpoke 35 and 56 lenses (though they can be slower to track initially.

Also, unlike AF-S, AF-C works at shooting aperture only, so you'll definitely want a larger aperture (f/2 - f/2.8 minimum in very low light). ...and don't use the smallest focus box (Single Point) for AF-C ever, it just doesn't work well, the dimmer the light, the bigger the focus box needs to be. The zone box seems to be the way to go for distant and/or isolated subjects like birds in flight (or maybe race cars etc.), but I find that single point tends to lock on a closer subject where I want it to, while zone will miss the target and pick a peripheral feature instead (or the wrong feature on the subject),YMMV.

For the fastest, most responsive AF try custom AF-C setting #6: Tracking Sensitivity: 0, Speed Tracking Sensitivity: 2, Zone Area Switching: FRONT (CENTER might work better if the subject isn’t coming right at you). I find that of the factory presets, #4 has the snappiest response time - I use it with my X-T20 which doesn’t have a mode #6 option. This also works very well in continuous shooting mode - I recommend CL mode, 5 fps or less unless you have lots of light and a contrasty subject. Use a slower speed with slower, older lenses. Again, YMMV. I do have BBF set up to work in M mode so I can easily focus, recompose and shoot with static subjects. In S mode I use the shutter button half-press and recompose method (with release priority). It sounds complicated, but it’s super simple once you get your head around it.

So with just moving the front AF switch, I get:

M mode - either manual focus or BBF single point (focus is automatically decoupled from the shutter button in M mode)

C mode - fast, accurate focus for moving subjects with a full press of the shutter button, or continuous tracking with a half-press (which can work quite well in some situations if you switch to Wide Tracking AF).

S mode - full button press if the focus box is on the subject, or half-press and recompose if it isn’t.

Lots of options for almost any situation just by rotating the little front switch (which can be done easily on the fly as the moment requires with your eye in the EVF). I use this on my X-T2 and X-T20 but it should be adaptable to any of the X-Trans III or IV cameras (although the newest cameras MIGHT work better with the DSLR method of continuous tracking). I use the rear command dial for AF On, and the AFL button for Focus Check, I hope some of that makes sense.

Hi Erik, Thanks for your explanation in details. It really helps a lot. Especially the AF-C mode, it seems works quite well. Because most of my lens are old and slow, I didn't use AFC that often. After firmware update, I will try more.

As to AF-S, I set the BBF on the AE-L button (I feel more confirortable and stable with AE-L than AF-L). And using rear command dial for Focus check (I feel this command dial button is harder than other button). So far this setup works quite well. I

I am trying M mode + BBF today. It shuld be kind of "focus jump" check this link: https://drive.google.com/file/d/1CEpgbOS3-W_2gR3ZRB8rkinAgXVRZrPZ/view?usp=drivesdk

The "focus jump" happens, when using BBF+M mode on my xt3+56.2. There will be no jump when fully manual focus by roating the focus ring.

My guess is the BBF is assigned by the firmware. Maybe this issue could be solve by the firmware update.

 WayneDST's gear list:WayneDST's gear list
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WayneDST
OP WayneDST Forum Member • Posts: 52
Re: Is anyone experience "back button focus" issue like this?

Ulrik Christiansen wrote:

WayneDST wrote:

Hi Ulrik, yes, that's what I experiencd.

I am using 56.2 too. Maybe this combination will cause the issue. Here is a video I made. You can see the first few second, M mode, when I press the shutter button. You can easily see the focus jump few cm.

At the same time, I can hear there is a sound, kind of motor rotating. But it sounds different as the sound during auto focusing.

Here is the video. I did few times of BBF test, the first time has issue.

https://drive.google.com/file/d/1CEpgbOS3-W_2gR3ZRB8rkinAgXVRZrPZ/view?usp=drivesdk

Yes, exactly the same behavior with my x-t3 56 setup. But works fine with my x-t20.

I hope they will fix it, since I had gotten used to shooting this way with bbf and manual. Lets see.

The other user I talked with also experienced this with other lenses than the 56.

I assume that could be conflict between M(manual mode) and BBF(auto focus). I did similar test with AF-S, and it works fine. Hope this jump will not damage the auto focus components. I rather using AF-S until it fix.
However, I found the combination of provides similar workflow. Only difference is that I can't check the focus peak on screen immediately.

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Erik Baumgartner Senior Member • Posts: 3,212
Re: Is anyone experience "back button focus" issue like this?

WayneDST wrote:

I am trying M mode + BBF today. It shuld be kind of "focus jump" check this link: https://drive.google.com/file/d/1CEpgbOS3-W_2gR3ZRB8rkinAgXVRZrPZ/view?usp=drivesdk

The "focus jump" happens, when using BBF+M mode on my xt3+56.2. There will be no jump when fully manual focus by roating the focus ring.

My guess is the BBF is assigned by the firmware. Maybe this issue could be solve by the firmware update.

Hi Wayne, I’ve heard of that focus jumping problem before with the 56, but I’ve never had mine do it (X-T2/X-T20). It’s hard to see what’s going on in the video, but I assume it focuses normally with the button and then intermittently jumps when you press the shutter button?

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WayneDST
OP WayneDST Forum Member • Posts: 52
Re: Is anyone experience "back button focus" issue like this?

Erik Baumgartner wrote:

WayneDST wrote:

I am trying M mode + BBF today. It shuld be kind of "focus jump" check this link: https://drive.google.com/file/d/1CEpgbOS3-W_2gR3ZRB8rkinAgXVRZrPZ/view?usp=drivesdk

The "focus jump" happens, when using BBF+M mode on my xt3+56.2. There will be no jump when fully manual focus by roating the focus ring.

My guess is the BBF is assigned by the firmware. Maybe this issue could be solve by the firmware update.

Hi Wayne, I’ve heard of that focus jumping problem before with the 56, but I’ve never had mine do it (X-T2/X-T20). It’s hard to see what’s going on in the video, but I assume it focuses normally with the button and then intermittently jumps when you press the shutter button?

Hi Erik, yes. It may happen intermittently. If I use half pressed shutter button for AF, it's not able to observe if there is a jump or not.
It seems only happen on BBF. Is it normal?

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Ulrik Christiansen
Ulrik Christiansen Senior Member • Posts: 1,693
Re: Is anyone experience "back button focus" issue like this?

WayneDST wrote:

Erik Baumgartner wrote:

WayneDST wrote:

I am trying M mode + BBF today. It shuld be kind of "focus jump" check this link: https://drive.google.com/file/d/1CEpgbOS3-W_2gR3ZRB8rkinAgXVRZrPZ/view?usp=drivesdk

The "focus jump" happens, when using BBF+M mode on my xt3+56.2. There will be no jump when fully manual focus by roating the focus ring.

My guess is the BBF is assigned by the firmware. Maybe this issue could be solve by the firmware update.

Hi Wayne, I’ve heard of that focus jumping problem before with the 56, but I’ve never had mine do it (X-T2/X-T20). It’s hard to see what’s going on in the video, but I assume it focuses normally with the button and then intermittently jumps when you press the shutter button?

Hi Erik, yes. It may happen intermittently. If I use half pressed shutter button for AF, it's not able to observe if there is a jump or not.
It seems only happen on BBF. Is it normal?

As far as I know, It is not normal with the x-t20. Mine only does it with the x-t3 and firmware 4.

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Canon PowerShot G7 X Fujifilm X-T20 Fujifilm XF 35mm F1.4 R Fujifilm XF 18-55mm F2.8-4 R LM OIS Fujifilm XF 55-200mm F3.5-4.8 R LM OIS +5 more
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