AF-F mode bug on D7200 ?

[SaintGermain]

Hello,

I"m trying to understand the AF mode "AF-F" with my D7200 and it seems that I found a bug.

Full-time servo AF: For moving subjects. Camera focuses AF-F continuously until shutter-release button is pressed. Focus locks when shutter-release button is pressed halfway.

When I am using AF-F mode with an object in focus, I am pressing the shutter in order to lock the focus. I was expecting the focus to remain the same (except that it is locked now) but I immediatly lose the focus and the AF is then struggling to reacquire focus again before locking.

In addition, the lock is only valid as long as I keep the shutter-release button half-pressed. As soon as I release the button, I am losing the focus lock.

Is this behavior intented ?

If not, do you have the same on your D7200 ?

Thanks

 

[BirgerH]

Hello,

I"m trying to understand the AF mode "AF-F" with my D7200 and it seems that I found a bug.

Full-time servo AF: For moving subjects. Camera focuses AF-F continuously until shutter-release button is pressed. Focus locks when shutter-release button is pressed halfway.

When I am using AF-F mode with an object in focus, I am pressing the shutter in order to lock the focus. I was expecting the focus to remain the same (except that it is locked now) but I immediatly lose the focus and the AF is then struggling to reacquire focus again before locking.

In addition, the lock is only valid as long as I keep the shutter-release button half-pressed. As soon as I release the button, I am losing the focus lock.

Is this behavior intented ?

If not, do you have the same on your D7200 ?

Thanks

Yes - I think you misunderstand the "lock"-word.

In AF-S, the camera locks at a distance - so you can use compose/recompose.

In AF-F the camera "locks" to a subject - and will try to follow the subject, if it moves - or if you move the camera - as long as you keep the shutter-button half-pressed. It will find another subject, when you release the shutter-button.

AF-F is analog to AF-C when using PDAF - except for not being that fast as the AF-C - and in my experience, not as efficient.

The behavior is very much intended

Birger.

 

[SaintGermain]

In AF-S, the camera locks at a distance - so you can use compose/recompose.

In AF-F the camera "locks" to a subject - and will try to follow the subject, if it moves - or if you move the camera - as long as you keep the shutter-button half-pressed. It will find another subject, when you release the shutter-button.

AF-F is analog to AF-C when using PDAF - except for not being that fast as the AF-C - and in my experience, not as efficient.

The behavior is very much intended

Hum that's not really what I am observing.

If I used AF-F and half-press the shutter on an object. The focus will never ever change whatever I am doing after that and whatever the object is doing.

Can you check that if you half-press the shutter in AF-F, the focus can really change ?

Thanks

 

[BirgerH]

In AF-S, the camera locks at a distance - so you can use compose/recompose.

In AF-F the camera "locks" to a subject - and will try to follow the subject, if it moves - or if you move the camera - as long as you keep the shutter-button half-pressed. It will find another subject, when you release the shutter-button.

AF-F is analog to AF-C when using PDAF - except for not being that fast as the AF-C - and in my experience, not as efficient.

The behavior is very much intended

Hum that's not really what I am observing.

If I used AF-F and half-press the shutter on an object. The focus will never ever change whatever I am doing after that and whatever the object is doing.

Can you check that if you half-press the shutter in AF-F, the focus can really change ?

Thanks

No - seems, that I was a little incorrect. It will (in AF-F) lock to a subject, keeping the (moving) subject in focus, while you are panning (following the subject) - even if the distance to the subject change. You need to keep the subject in the focus square.

If you use AF-S for this, and the subject distance change, while following the subject, the subject will be out of focus.

If using AF-F together with AF-area "Follow Motiv" - it should follow a motiv that is passing through the scene (I have never tried - don't know how good it works).

BirgerH.

 

[SaintGermain]

In AF-S, the camera locks at a distance - so you can use compose/recompose.

In AF-F the camera "locks" to a subject - and will try to follow the subject, if it moves - or if you move the camera - as long as you keep the shutter-button half-pressed. It will find another subject, when you release the shutter-button.

AF-F is analog to AF-C when using PDAF - except for not being that fast as the AF-C - and in my experience, not as efficient.

The behavior is very much intended

Hum that's not really what I am observing.

If I used AF-F and half-press the shutter on an object. The focus will never ever change whatever I am doing after that and whatever the object is doing.

Can you check that if you half-press the shutter in AF-F, the focus can really change ?

Thanks

No - seems, that I was a little incorrect. It will (in AF-F) lock to a subject, keeping the (moving) subject in focus, while you are panning (following the subject) - even if the distance to the subject change. You need to keep the subject in the focus square.

If you use AF-S for this, and the subject distance change, while following the subject, the subject will be out of focus.

If using AF-F together with AF-area "Follow Motiv" - it should follow a motiv that is passing through the scene (I have never tried - don't know how good it works).

I just tried again in AF-F mode with Normal-area AF, and it doesn't work as you described.

If I half-press the shutter, whatever I do afterwards, cannot change focus.

For instance I can keep an object on the focus square, half-press the shutter, and if I step close, the object will be out of focus.

Do you have really D7200 ? Or perhaps my D7200 is faulty...

 

[BirgerH]

In AF-S, the camera locks at a distance - so you can use compose/recompose.

In AF-F the camera "locks" to a subject - and will try to follow the subject, if it moves - or if you move the camera - as long as you keep the shutter-button half-pressed. It will find another subject, when you release the shutter-button.

AF-F is analog to AF-C when using PDAF - except for not being that fast as the AF-C - and in my experience, not as efficient.

The behavior is very much intended

Hum that's not really what I am observing.

If I used AF-F and half-press the shutter on an object. The focus will never ever change whatever I am doing after that and whatever the object is doing.

Can you check that if you half-press the shutter in AF-F, the focus can really change ?

Thanks

No - seems, that I was a little incorrect. It will (in AF-F) lock to a subject, keeping the (moving) subject in focus, while you are panning (following the subject) - even if the distance to the subject change. You need to keep the subject in the focus square.

If you use AF-S for this, and the subject distance change, while following the subject, the subject will be out of focus.

If using AF-F together with AF-area "Follow Motiv" - it should follow a motiv that is passing through the scene (I have never tried - don't know how good it works).

I just tried again in AF-F mode with Normal-area AF, and it doesn't work as you described.

If I half-press the shutter, whatever I do afterwards, cannot change focus.

For instance I can keep an object on the focus square, half-press the shutter, and if I step close, the object will be out of focus.

Do you have really D7200 ? Or perhaps my D7200 is faulty...

No - I have a D7000.

I just tried (I never use LiveView - and haven't really tried the AF-F seriously) - and it doesn't work as I described - not all the time, anyway.

I have to reread and study the AF LiveView modes a little more - I have some e-boks to help me - I'll be back tomorrow (it's late here) if you like and have the time to wait - and sorry for not being correct

BirgerH

 

[Gruja]

D7200 is not that great in Live View mode. I played a bit with AF-F and it does change focus even if shutter button is not half-pressed. But not as fast. It seems like it waits for few seconds before it decides to hunt for new focus. I guess idea is to keep focus more steady and not change it constantly, since change is not smooth and looks bad on video. Btw. do you know that you can use OK button to begin tracking of current target? In that case it sticks to target as long as it can, but hunts all the time. And if you don't want that hunting focus just use AF-S instead of AF-F.

What's scenario you want to cover with Live view and AF-F?

 

[SaintGermain]

D7200 is not that great in Live View mode. I played a bit with AF-F and it does change focus even if shutter button is not half-pressed. But not as fast. It seems like it waits for few seconds before it decides to hunt for new focus. I guess idea is to keep focus more steady and not change it constantly, since change is not smooth and looks bad on video. Btw. do you know that you can use OK button to begin tracking of current target? In that case it sticks to target as long as it can, but hunts all the time. And if you don't want that hunting focus just use AF-S instead of AF-F.

What's scenario you want to cover with Live view and AF-F?

Hello,

Perhaps I was not clear in describing the bug ?

The problem was not in achieving continuous focus while in AF-F mode (that works without problem in good light) but locking that focus.

Perhaps you can point to the points which were not clear in my original message ?

English is not my native language, so perhaps I used some incorrect words.

Cheers,

 

[Gruja]

I reread all messages in a thread. If I understood you correctly, it behaves as you described on my D7200 as well. Here are possible combinations for AF-F:

AF-F, shutter button is not pressed - it hunts for focus.

AF-F, shutter is half pressed - focus distance is locked. If you release button, it will hunt again. If you keep it helf-pressed but subject (or you) move - focus distance will remain same and subject will be out of focus.

Now if you want to lock focus to subject and not to distance, so that it adapts as you or subject move, you should use AF-F with tracking mode and press OK instead of half pressing shutter to lock to a target. However once you press shutter it will hunt for focus one more time which makes this tracking a bit pointless.

There's an option in a menu - Custom Settings a4 - AF activation. If you set it to "AF ON only", shutter button will no longer cause refocusing. So you can use AF-F, tracking mode and OK button for locking to subject, and just click when you like what you see.

But again, question is why you're using Live view focusing in the first place? Except if it is for video. Viewfinder focusing is where D7200 shines and you'll probably be better with it.

 

[SaintGermain]

I reread all messages in a thread. If I understood you correctly, it behaves as you described on my D7200 as well. Here are possible combinations for AF-F:

AF-F, shutter button is not pressed - it hunts for focus.

AF-F, shutter is half pressed - focus distance is locked. If you release button, it will hunt again. If you keep it helf-pressed but subject (or you) move - focus distance will remain same and subject will be out of focus.

Yes that's the problem : when I half-press the release button, 3 things are happening : I immediately lose focus, the AF try to get the focus again, and when the focus is achieved, only then do I get a focus lock.

Now if you want to lock focus to subject and not to distance, so that it adapts as you or subject move, you should use AF-F with tracking mode and press OK instead of half pressing shutter to lock to a target. However once you press shutter it will hunt for focus one more time which makes this tracking a bit pointless.

No I don't try to lock on a subject and I understand that the relevant AF-area mode for that is "Subject-tracking AF". I am currently using the AF-area mode "Normal-area AF".

It is BirgerH who said that we should have focus lock on the subject in that AF-area mode, not me. I specifically said that it doesn't work that way and we only got focus lock on the distance. Then Birger said that he will check again.

There's an option in a menu - Custom Settings a4 - AF activation. If you set it to "AF ON only", shutter button will no longer cause refocusing. So you can use AF-F, tracking mode and OK button for locking to subject, and just click when you like what you see.

I don't try to get focus lock on the subject, I am tryng to get focus lock on the distance.

It is working, but only after losing focus and getting it again. For me that's a bug.

If I try using AF-ON instead of the shutter release button, I got the same result : I immediately lose focus.

But again, question is why you're using Live view focusing in the first place? Except if it is for video. Viewfinder focusing is where D7200 shines and you'll probably be better with it.

I want to use it for both videos and photos. Live view has its use, when the viewfinder cannot be used. However the question was not how to find a workaround for this problem but to confirm a bug.

Thanks for trying to help me, but unfortunately it seems that we are not really talking about the same things...

 

[Gruja]

I don't try to get focus lock on the subject, I am tryng to get focus lock on the distance.

For that case you should not use AF-F but AF-S. It will stick to fixed distance after half-press.

It is working, but only after losing focus and getting it again. For me that's a bug.

Yes, that refocusing is jerky. It could be called a bug since in AF-F scenario you already had it focused, and now it jumps around to acquire exact same focus on same distance. Is this the problem that bothers you most? If so, there's one way to avoid it. Find custom menu f4 "Assign AE-L/AF-L button" and set it to "AF lock only". Now, as AF-F tracks what you want and you want to lock current focus distance at some point, just press and hold AF-L button. It will not refocus, just keep current distance. Then you can press shooter button later, it also won't refocus.

Alternative solution is to change AF/M switch to M mode. Cumbersome but maybe useful if you need it for longer period.

I want to use it for both videos and photos. Live view has its use, when the viewfinder cannot be used. However the question was not how to find a workaround for this problem but to confirm a bug.

I agree that Live view has its use, it's just unfortunate that on Nikon it's slow, jerky and not fluid at all. Whenever I tried to shoot video, I was always fighting with AF. In my opinion it's best to avoid changing focus during video sequence, or do it manually. Since that doesn't fit my casual needs I just gave up on DSLR and use RX100 for video.

 

[SaintGermain]

I don't try to get focus lock on the subject, I am tryng to get focus lock on the distance.

For that case you should not use AF-F but AF-S. It will stick to fixed distance after half-press.

Except if I want a continuous focus before locking it. Which was the entire point of AF-F.

It is working, but only after losing focus and getting it again. For me that's a bug.

Yes, that refocusing is jerky. It could be called a bug since in AF-F scenario you already had it focused, and now it jumps around to acquire exact same focus on same distance. Is this the problem that bothers you most?

Yes that behavior doesn't make sense to me, especially with your given workaround below.

If so, there's one way to avoid it. Find custom menu f4 "Assign AE-L/AF-L button" and set it to "AF lock only". Now, as AF-F tracks what you want and you want to lock current focus distance at some point, just press and hold AF-L button. It will not refocus, just keep current distance. Then you can press shooter button later, it also won't refocus.

Thanks ! I will be using your workaround. That is the correct behavior in my opinion (no reason to focus again when you have the focus). Using the shutter release trigger a bug I think.

Alternative solution is to change AF/M switch to M mode. Cumbersome but maybe useful if you need it for longer period.

I want to use it for both videos and photos. Live view has its use, when the viewfinder cannot be used. However the question was not how to find a workaround for this problem but to confirm a bug.

I agree that Live view has its use, it's just unfortunate that on Nikon it's slow, jerky and not fluid at all. Whenever I tried to shoot video, I was always fighting with AF. In my opinion it's best to avoid changing focus during video sequence, or do it manually. Since that doesn't fit my casual needs I just gave up on DSLR and use RX100 for video.

Indeed, however it is better than nothing. And as I am not really used to focus manually, it has its use for me for the moment.

Thanks for the workaround and the confirmed bug.

 

[Gruja]

I'm glad we two non-native speakers found a way to communicate complex issue and how to fight it. Cheers!

 

[SaintGermain]

I'm glad we two non-native speakers found a way to communicate complex issue and how to fight it. Cheers!

Thanks for having taken the time to help me !

 

[BirgerH]

I'm glad we two non-native speakers found a way to communicate complex issue and how to fight it. Cheers!

Thanks for having taken the time to help me !

And...

I have done some rereading, as promised.

Gruja is right - here's from Darrell Young's "Mastering the D7000":

"Subject-Tracking AF:

When autofocus is locked in—either by using the Shutter-release button in AF-S mode or automatically in AF-F mode (discussed previously)—this mode lets you start subject tracking with the OK button.

When the subject is selected (after you press the OK button) the camera locks its attention on the subject and tracks it whether the subject or the camera moves."

Hope it's useful - I'm not sure, I would ever use it - seems to me to be a little unpredictable

BirgerH.

 

[SaintGermain]

I'm glad we two non-native speakers found a way to communicate complex issue and how to fight it. Cheers!

Thanks for having taken the time to help me !

And...

I have done some rereading, as promised.

Gruja is right - here's from Darrell Young's "Mastering the D7000":

"Subject-Tracking AF:

When autofocus is locked in—either by using the Shutter-release button in AF-S mode or automatically in AF-F mode (discussed previously)—this mode lets you start subject tracking with the OK button.

When the subject is selected (after you press the OK button) the camera locks its attention on the subject and tracks it whether the subject or the camera moves."

Hope it's useful - I'm not sure, I would ever use it - seems to me to be a little unpredictable

Subject-Tracking AF works as expected for me.

The problem was with AF-F and focus lock on the distance (NOT on the subject).

And either with "AF-F+Subject-Tracking AF" or "AF-F+Normal-area AF", the result is the same: as soon as you press the shutter release button to lock the focus (on the DISTANCE, not on the subject) you lose the focus. This does not happen if you use the AF-ON button.

Gruja confirmed that it was a bug. That's all I was asking for.