5D4 - can't use live view focus when configured for back button focus

[strutzj]

I use the shutter button to meter only and the AF-ON button to focus in servo mode. However, my live view focus doesn't work. There are references to this issue in this forum and elsewhere but nobody seems to give an explanation or work-around. I can do both (back button focus and live view focus) with my 90D and SL3, surely the 5D4 should also be able to do it. 

[Waddizzle]

 My 6D2 does not respond to Touch AF in Live View when AF is disabled on the Shutter.

That is, it does not respond to Touch AF as long as the [LOCK] button is switched to LOCK.

[strutzj]

My Lock button was 'on' (right position) and for a second I was hopeful that was my problem but no. It's a multi-function lock and wasn't set to the touch screen. 

Good thought though....

[RobertTheFat]

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@strutzj wrote:

Nope, I disagree. I also have a 90D and an SL3; they're set up *exactly-the-same-way" and they work as expected; that is the back button focusing works by pressing the AF-ON button while the live view focus occurs when you touch the back touch screen. ***The 5D4 does not work the same way***. 

All three camera setups: shutter button = "metering start", AF-ON button = "metering and AF start". This is the wording from the menu.

The live view focus system works separately from the viewfinder focus system. The viewfinder focus system uses a separate focus sensor while the live view focus system utilizes the image sensor. Removing focus from the shutter button should have absolutely nothing  to do with live view (screen touch) focusing. 

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So "The 5D4 does not work the same way [as the 90D and the SL3]"? OK, I'll accept that. But since I believe that those other two cameras are more recent, I guess I'd phrase it the other way around: The 90D and the SL3 do not work the same way as the 5D4. Case closed?

[strutzj]

The answer may well be that the 90D and SL3 facilitate touch focus while the camera is configured for BBF because they're newer than the 5D4.  

Case closed? I don't know, it's a guess but I don't have any better ideas. That's why I'm here. I accept that people here may not have any better ideas either short of knowing for sure - and that's okay. I'll continue to search for a more definitive answer. Somebody must know...

Thanks again for your help.

[Waddizzle]

No offense, but I am convinced it is a combination of camera settings holding it back.  This menu only appears in my 6D2 when the camera is actually Live View mode.  The 5D4 should have a similar menu.

[EDIT]. This would be much simpler if tried a camera reset.  To fully reset the camera, it must be done in at least 3 spots in the menus.

[strutzj]

Of course no offense taken. The 5D4 has the same "Touch Shutter" setting and it's enabled. The same page also has a "Live View Shoot" setting which is also enabled. 

The camera fires the shutter in live view but does not focus when configured for BBF. The image is not in focus. Switching the shutter button configuration from "meter only " to "meter & focus" enables the live view focusing. And someone here previously suggested that made sense but I don't think it does because the shutter isn't used for live view shooting - why would it disable live view focusing as well?