What advantage of rear-button AF setting?

garuda

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I have watched many Youtube vids on menu setting up the a7R iv. Many recommend a custom back button to trigger AF and therefore to disable the half-press-shutter function for AF. Does holding down back-button lock the AF, whereas the shutter releases AF during the 10-frame burst? I can’t detect any difference when switching back and forth between AF-ON back button and shutter half- depress. But still the seasoned shooters like the custom back button. Do we know why?
 

Kevriano

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I have watched many Youtube vids on menu setting up the a7R iv. Many recommend a custom back button to trigger AF and therefore to disable the half-press-shutter function for AF. Does holding down back-button lock the AF, whereas the shutter releases AF during the 10-frame burst? I can’t detect any difference when switching back and forth between AF-ON back button and shutter half- depress. But still the seasoned shooters like the custom back button. Do we know why?


You need to disable the shutter release with the front button for the back button to work properly, which it sounds like you may not have done. The advantage, for me at least, is that when shooting AFC for any subject, but especially birds in flight, the camera focusses continually as you fire the shutter. This leads to a higher hit rate IMO, less delay in shutter release. It's something I've used for 5 years and could never go back from now.
 

garuda

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Thanks Kev, I assume that to track a BIF target using rear-but AFC (shutter disabled), that the rear AF button must be depressed for the duration of the 5-10 frame burst. And AF will track regardless of where is bird in frame when area is set to Wide.

Also, on my older a7Rii my rear center button on wheel would activate the AF Lock-ON, then the second depress would lock on tracking the target regardless of where it appeared in frame and with no further depressing on any buttons while firing burst. But I don't see that option on R iv, even when I set a button to "STANDARD" like on the Rii.
 

Kevriano

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Yes, keep the button pressed for continuous AF and if you have tracking on, it should track your subject once locked on. I use the focus hold button on the 200 600 when I remember, I can't get on with using the centre button on the wheel. I'd have to delve into the menus to see if it's possible.
 

Mark Winter

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I use back button focus and can vouch for its use, especially for birds in flight, but really anything that is quickly moving. And, as the others stated, you would continuously press that button when shooting multiple frames.
 

garuda

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I use the focus hold button on the 200 600
Thanks Kev & Mark. Couple more things ref AFC. I likely mistakenly thought lens AF-Hold locked the AF at fixed distance like in manual focus, so I don't use it on my 2-600 lens. Because I reasoned if the bird changes its distance from cam while on lens Hold, it'll go out of focus. So does lens Hold button lock the AF Tracking function or lock the focus at a fixed distance like in man focus?

P.S. Kev - I found that later iterations of a7R cams that Sony replaced the old wheel's center button Tracking Lock with an integrated AF-Tracking lock embedded in AFC. So that old "Standard Focus" tracking system is gone and replaced.
 
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Kevriano

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Thanks Kev & Mark. Couple more things ref AFC. I likely mistakenly thought lens AF-Hold locked the AF at fixed distance like in manual focus, so I don't use it on my 2-600 lens. Because I reasoned if the bird changes its distance from cam while on lens Hold, it'll go out of focus. So does lens Hold button lock the AF Tracking function or lock the focus at a fixed distance like in man focus?

P.S. Kev - I found that later iterations of a7R cams that Sony replaced the old wheel's center button Tracking Lock with an integrated AF-Tracking lock embedded in AFC. So that old "Standard Focus" tracking system is gone and replaced.


I've found focus hold on the lens literally keeps the focus point at where you set it, so you can focus on a bird dead centre, and then move sideways from it and it will stay focussed on the plane you were on.
 

garuda

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I've found focus hold on the lens literally keeps the focus point at where you set it, so you can focus on a bird dead centre, and then move sideways from it and it will stay focussed on the plane you were on.
So if bird is stationary on a limb, I press/hold lens Hold, which over-rides my usual AFC preventing it from hunting focus needlessly. But if bird takes wing, I should release lens Hold and return to press/hold the rear-butt "AF-ON" to initiate AF tracking. Right? Because lens Hold locks to single plane regardless of cam movements in that focus area (usually Wide or Zone).
 

Kevriano

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So if bird is stationary on a limb, I press/hold lens Hold, which over-rides my usual AFC preventing it from hunting focus needlessly. But if bird takes wing, I should release lens Hold and return to press/hold the rear-butt "AF-ON" to initiate AF tracking. Right? Because lens Hold locks to single plane regardless of cam movements in that focus area (usually Wide or Zone).


Yes, basically that.
 

scotty38

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So if bird is stationary on a limb, I press/hold lens Hold, which over-rides my usual AFC preventing it from hunting focus needlessly. But if bird takes wing, I should release lens Hold and return to press/hold the rear-butt "AF-ON" to initiate AF tracking. Right? Because lens Hold locks to single plane regardless of cam movements in that focus area (usually Wide or Zone).

Surely if you are using BBF using the AF-ON button and you released the AF-ON button you're in focus-hold anyway so no need to have another button doing the same thing. I had believed focus-hold was useful for those folk NOT using BBF and hence needing to prevent hunting/refocussing when the shutter button is pressed?

Might have it round my neck though :)
 

Kevriano

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Surely if you are using BBF using the AF-ON button and you released the AF-ON button you're in focus-hold anyway so no need to have another button doing the same thing. I had believed focus-hold was useful for those folk NOT using BBF and hence needing to prevent hunting/refocussing when the shutter button is pressed?

Might have it round my neck though :)


No, BBF disables focus hold on the AF-On.
 

garuda

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No, BBF disables focus hold on the AF-On.
You guys are making my brain heat up weighing these arguments! I'm thinking if the BBF af-ON is held down then the lens motor remains alert/active even though the bird is sitting still (indicated by stationary or dancing squares on birds head in viewfinder). So the AF lens motor is poised to hunt even if it's currently holding with bird sitting still. But Kev believes the AF lens motor is disabled with Lens Hold button is pressed, which likely disengages motor's active poise to hunt. Seems both args are valid to some degree with efficiency and technical aspect being the pragmatic issue. My brain is over-heating now, I need a nap.
 
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Kevriano

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You guys are making my brain heat up weighing these arguments! I'm thinking if the BBF af-ON is held down then the lens motor remains alert/active even though the bird is sitting still (indicated by stationary or dancing squares on birds head in viewfinder). So the AF lens motor is poised to hunt even if it's currently holding with bird sitting still. But Kev believes the AF lens motor is disabled with Lens Hold button is pressed, which likely disengages motor's active poise to hunt. Seems both args are valid to some degree with efficiency and technical aspect being the pragmatic issue. My brain is over-heating now, I need a nap.


Give me an hour, I'll test.
 

scotty38

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No, BBF disables focus hold on the AF-On.
That makes no sense to me.... Using back button focus via the af-on button means the camera focuses while the button is pressed (assuming af-c of course otherwise why bother) so as soon as you release the button it stops focussing ie focus is held. What is the point of using BBF if it doesn’t work like this. Well it works like this for me.....
 

garuda

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That makes no sense to me.... Using back button focus via the af-on button means the camera focuses while the button is pressed (assuming af-c of course otherwise why bother) so as soon as you release the button it stops focussing ie focus is held. What is the point of using BBF if it doesn’t work like this. Well it works like this for me.....
I'm not pursing this for sake of argument, rather want clarity on how best to use AF & tracking together; which I assume is goal of all of us. But some explanations are getting confusing in interpretation.

So I describe my setting and reasoning, for both your opinion/comments - just to start w simplicity. BBF to me means any custom button assigned to rear of cam, for AF track in our case here. I chose AF-ON button for assigning the AFC & tracking function for BIF for thumb-conveniance mostly (along w need to disable the half-press shutter focus function.

In either Wide or Zone, I put target near center of VF and press/hold my AF-ON button. Little squares dance or large square encircles head, eyes, or body -- lock tracking target anywhere in the focus area chosen.

In my experience if AF-ON butt is released, it may loose both focus & tracking. This button function/arrangement mostly applies w BIF.

Ref Kev's suggestion, I assume using Lens lock button for stationary targets ensures locked focus on initial target regardless of slight cam movement or other birds/objects entering the focus area whether wide or zone. If bird is stationary, there's no need for AFC or tracking since Lens-lock focus is locked on exact distance betw bird and focal plane.

If my reasoning here is wrong, please correct me, as I want a clear understanding of this AF function.
 
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scotty38

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Hi Garuda, for me at least bbf is simply the method of removing the focussing task from the shutter button ie the assigned focus button (say AF-ON) does the focussing and the usual shutter button fires the shutter - two tasks two buttons. What this means is you can now set the camera to AF-C and have the best of both worlds ie while the button is pressed you are focussing (and tracking ie AF-C) continuously and when it's released you're not - but it is focussed on where it was pointed when you pressed the button (ie AF-S).

Obviously you need to remove the focus function from the shutter button as below:

AF w/ shutter (still image)​


Selects whether to focus automatically when you press the shutter button halfway down. Select [Off] to adjust the focus and the exposure separately.
  1. MENU →
    s_menu_shoot1.png
    (Camera Settings1) → [
    cE08C.png
    AF w/ shutter] → desired setting.

Menu item details

On: The auto focus operates when you press the shutter button halfway down.
Off: The auto focus does not operate even if you press the shutter button halfway down.

****************************************

And then set to release priority in AF-C:



Priority Set in AF-C​


Sets whether to release the shutter even if the subject is not in focus when the continuous AF is activated and the subject is in motion.
  1. MENU →
    s_menu_shoot1.png
    (Camera Settings1) → [Priority Set in AF-C] → desired setting.

Menu item details

AF: Prioritizes focusing. The shutter will not be released until the subject is in focus.
Release: Prioritizes the shutter's release. The shutter will be released even if the subject is out of focus.
Balanced Emphasis: Shoots with a balanced emphasis on both focusing and shutter release.


Does that help at all? I'm trying my best lol but I'm no teacher.......
 
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Kevriano

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I'm not pursing this for sake of argument, rather want clarity on how best to use AF & tracking together; which I assume is goal of all of us. But some explanations are getting confusing in interpretation.

So I describe my setting and reasoning, for both your opinion/comments - just to start w simplicity. BBF to me means any custom button assigned to rear of cam, for AF track in our case here. I chose AF-ON button for assigning the AFC & tracking function for BIF for thumb-conveniance mostly (along w need to disable the half-press shutter focus function.

In either Wide or Zone, I put target near center of VF and press/hold my AF-ON button. Little squares dance or large square encircles head, eyes, or body -- lock tracking target anywhere in the focus area chosen.

In my experience if AF-ON butt is released, it may loose both focus & tracking. This button function/arrangement mostly applies w BIF.

Ref Kev's suggestion, I assume using Lens lock button for stationary targets ensures locked focus on initial target regardless of slight cam movement or other birds/objects entering the focus area whether wide or zone. If bird is stationary, there's no need for AFC or tracking since Lens-lock focus is locked on exact distance betw bird and focal plane.

If my reasoning here is wrong, please correct me, as I want a clear understanding of this AF function.

This is right. If you use the focus lock it stays locked on your subject, which is what I was getting at. To refocus you have to release the focus lock and go back to the BBF button, which by default is the AF ON button.
 

DMoncla

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The biggest benefit of BBF is being able to let go and your focus is locked on certain spot/plane. If you use the shutter button to focus you can never lock you focus without the use of another button such as the button on the lens or the BBF button you just reprogrammed for BBF anyway. If there is branch where a bird always lands and you have locked your focus on that spot you can just press the shutter when a new bird lands in that spot. There are all sorts of benefits to using BBF and I can't think of any to use the shutter button for it at all accept the few shots you'll miss as you get used to switching. Once you do you will never want to go back.
 

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