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A7R III AF puzzle

Ziggy99

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Wonder if the brains trust can help with this ...

I'd read that in drive mode H+, focus was only achieved on the first shot in AF-C. For interest I tested this. True.

But it also proved true of H and M! Moving to different objects, well lit and contrasty, didn't provoke changed focus.

It does CAF when I do a dry run without the shutter pressed. The shutter is separated from AF. It's an FE 100-400 & 1.4 TC so running at f8.

I'm sure there's something simple I'll kick myself for overlooking.
 

bdbits

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A shot in the dark, but I seem to recall there is a focus priority setting that might be influencing this. I remember seeing it (on my A7Riii) but don't have my camera with me at the moment, but maybe that will jog your memory. I can look through the menus when I get home. Not 100% sure that is even it, but maybe.
 

Ziggy99

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Thanks Bob, I'll have a look. My recollection is that focus priority is set to 4.

I tested the bare 100-400 and it failed to CAF too. I cleaned the contacts to no effect. But the 24-105 did CAF. So different lens, different aperture.
 

bdbits

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I am still learning all the stuff on this A7Riii (I think you have the A9?) but here goes anyway...

Menu group 1, page 6/14 has AF Track Sens - which I think is the one you are referring to, and 4 is more responsive (3 is default) so that seems reasonable. Could try 5 I suppose.

The prior page 5/14 has Priority Set in AF-S and Priority Set in AF-C, which is what I think I was remembering. Not sure if this would explain the behavior you are seeing or not. Might be worth playing with but would probably reduce the frame rate if focus is the priority. The default is Balanced as one might expect. From the help page for my A7Riii.

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.

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.


Edit: this might prove useful for the A9.
http://support.d-imaging.sony.co.jp/support/ilc/autofocus/ilce9/en/index.html
 

Ziggy99

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Thanks Bob.
As per the title it's the A7R III that's providing the puzzle.

Release/focus is balanced.
The 100-400 lens works fine on the A9.
The 400 2.8 & 2x TC doesn't CAF on the 7R III & while the the 24-105 does.
The 100-400 lens firmware is current; ditto the body.
Edit: wrong on the body firmware! It's 3.01 and should be 3.10.
Edit 2: no change.
 
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bdbits

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Ziggy99

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It's very kind of you to help Bob, thanks.

That link is food for thought. I'll revise the test to make sure the caveats don't apply. I don't think they do but best to be sure before I take the body back to the dealer.
 

Ziggy99

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Just to be sure I reinitialised the body and repeated a couple of tests. The 100-400 again failed to CAF and record while the 24-105 succeeded :confused:
 

bdbits

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I think at this point that is probably the best course of action. Let us know in 4-6 weels if they managed to fix it or not.
 

Ziggy99

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Another FB suggestion was to check the focus lock button on the lens and that's pretty good thinking.
It's possible to accidentally press and release one as the buttons are under neoprene. On the 100-400 though it makes a bit of a sound and can usually be felt; on the 400 2.8 much less so.
But I don't think it's probable. Never had it on the A9. Has to have happened each of the dozen or so times I did CAF and recorded and none of the 2-3 times I did CAF only as a dry run.
 

Ziggy99

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So it went back to the dealer who sent it off to the techs.
They couldn't reproduce the failure and they did have an FE100-400 for the tests. They used fresh cards and battery and cleaned everything. They said they did some AF optimising (don't know how that works).
At home I put it through the same set of 4 tests and it failed on 3. It worked on the 4th only because the tech had set Focus/Release balance to Focus and the unit stuttered its way through at about half speed.
Same deal as before: it would CAF fine on a dry run (ie no recording) but not while recording.
I'll take it out bird shooting again and see if I can live with it. Otherwise it will probably become a claim under consumer law.
 

bdbits

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Really sorry to hear your issue is unresolved.

Have you by chance posted this over on FM (fredmiranda.com)? I lurk around in the shadows over there, enough to know FM has a lot of pros (including bird shooters) who use the A7Riii and/or the 100-400, though not necessarily together. Still, might be worth a shot (no pun intended) if you have not been there.
 

bdbits

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I hear you. DPReview is by far the worst I have been to (in my opinion) for arguing, so much so I seldom drop in there any more. Sadly FM seems to have gotten a little worse in the last year or so.

This is the best site for emount gear in my opinion, but we are a bit smaller community.
 

Ziggy99

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Yes, DPReview is a bearbit.
There's multiple forums for Sony and the talent is too divided IMO. FB mostly remains at the kinder level.
 

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