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X-T2 Problem with Release/Focus priority

release focus priority X-T2

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#1 Hugo G

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Posted 31 July 2017 - 06:38 PM

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My X-T2 doesn´t switch to release priority anymore. It is stuck in focus priority even though release priority is selected.

The latest firmware is installed (also on the lens(es))

It happens in all focus modes and with different lenses.

I remember that it worked once to switch between the two modes. Unfortunately I only now realized that it doesn´t switch anymore thus I cannot determine if a FW update or whatever created this problem...

 

 

Anyone else with the same problem?

I only find threads on the internet without any answers.
I also tried to get an answer from Fujifilm support, but they haven´t replied.



#2 Doug Pardee

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Posted 01 August 2017 - 03:37 PM

What is it doing, and what do you expect it to do?



#3 Hugo G

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Posted 01 August 2017 - 04:31 PM

It is set to release priority.

So I expect it to take a picture when I press the shutter, even if it is not in focus yet.

But what it does is when I press the shutter and it is still trying to focus it doesnt take a picture or there is a delay until it is in focus and then takes a picture.


Edited by Hugo G, 01 August 2017 - 04:33 PM.


#4 Doug Pardee

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Posted 01 August 2017 - 07:12 PM

That's what Fujifilm's Release Priority does. Fuji will never take a picture while focusing is still in progress -- it always waits for focus to complete. The Release Priority tells it that if the focus completes as a "failure" (!AF would display in the viewfinder) to go ahead and take a picture anyway.

 

With contrast-detect autofocus (CDAF), that's probably a wasted shot, because you don't know where contrast detect will leave the focus when the camera gives up and declares failure. With phase-detect autofocus (PDAF), the lens probably never changed focus, and that's more likely to be usable -- especially during burst shooting.

 

Note that with single-point AF, a PDAF failure will result in the camera switching to CDAF and trying that, so Release Priority rarely will give a usable picture with failed single-point AF. Big exception: single-point AF (on a PDAF point of course) with AF-C and CH and aperture of f/8 or wider will never try CDAF even if PDAF fails -- again, we're talking about a burst shooting setup. If you use single-point AF and sometimes do burst shooting, my personal recommendation is to set Focus Priority for AF-S and Release Priority for AF-C.

 

PDAF failure is close to instantaneous. It sounds like you're experiencing CDAF failure -- either because you're using a configuration that only uses CDAF, or more likely you're using single-point PDAF and the camera is trying CDAF when PDAF fails.


Edited by Doug Pardee, 01 August 2017 - 07:27 PM.


#5 Hugo G

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Posted 02 August 2017 - 04:51 PM

First of all thank you very much for this indepth answer!
 

I just did a quick test to understand what you were saying. I tried to focus on a subject way too close for my camera and in release priority it took a picture and in focus priority it didn't.

 

So it seems it is not a fault of the software but rather wrong expectaions on my side.

 

Althhough I have to say that it still feels like a strange behavior of the camera. I for example have the focus lever on manual and at the same time have the back button set to continious auto focus with a single point (.i.e. having the advantage of manual focus and auto focus at the same time). The shooting mode is set to CL.

When I just tip the backbutton and then press immediately the shutter, no picture is taken. Therefore the camera feels extremely laggy.

Is this behavior normal and still falls under what you explained?

 

And may I ask where do you have this information from? / Where can one read more about this (specific behavior for the Fuji)?
As the manual only states regarding shutter priority: "Shutter response is prioritized over focus. Pictures can be taken when the camera is not in focus."

 

EDIT: Ok just read about phase and contrast detection. And found the place in the manual where it shows phase vs contrast focus points (p. 79 if anyone is reading) Is it correct that the focus points in the centre are all hybrid?


Edited by Hugo G, 02 August 2017 - 05:11 PM.


#6 Doug Pardee

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Posted 03 August 2017 - 02:58 PM

I don't know exactly how that camera handles back-button AF-C with AF-M -- the X-T2 has a separate "Shutter AF" option for disengaging AF from the shutter release and my X-T10 doesn't -- so I can't help you there. I'd assume, however, that it's normal -- the camera's just waiting for the lens to finish focusing.

 

I personally don't recommend back-button AF-C for general use. If you really need AF-C, then you need it. But if you've got it set to AF-C just in case someday you want AF-C, be aware that if your shooting aperture is at f/9 or higher, the camera will not use phase-detect AF. If you're controlling the aperture, it's usually easy enough to avoid that issue. But if you're shooting P mode, in daylight the camera might select f/9 or higher, leaving you with unnecessarily slow contrast-detect AF.

 

Fujifilm doesn't publish most of this stuff. That's why there are so many third-party books, such as Rico Pfirstinger's that are advertised on this site. Pfirstinger, for example, recommends skipping AF-C for simple tracking AF when you're only going to take one shot. He recommends using AF-S and "mashing" the shutter button down in one stroke, skipping the half-press. That way, as soon as the lens has focused, the shutter is released. That should give AF results as accurate as AF-C.

 

And yes, in single-point AF, the camera will try CDAF if PDAF fails, regardless of which PDAF point you select. Unless you're in AF-C with CH drive, in which case the camera uses only PDAF at apertures of f/8 or below, and only CDAF at apertures of f/9 or above.


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Also tagged with one or more of these keywords: release, focus, priority, X-T2