Richard Barbour Asks Why Turn Off Shutter AF When Using Back Button AF?

Posted May. 27th, 2017 by Daniel J. Cox

Hi Dan,
I’ve had the G85 for a short time and enjoyed reading your review, especially the explanations of the various settings you use. I also like to use back-button focus, but not all of the time, so I was confused by your settings where you say to set “Shutter AF” to OFF. I have it set to ON, and back-button focus works fine when I use it, but otherwise, the focus will lock when I half-press the shutter. This lets me have it either way; am I missing something?

AF/AE Lock button that is setup on the GH5 for Back Button AF.

Richard, the reason I set “Shutter AF” to OFF is due to the fact that, yes, the back button will also initiate AF but having both Shuter Button focusing AND the Back Button Focusing, they negate each other. The reason we use Back Button AF is to separate focus activation from the shutter button. The reason for using Back Button AF is to be able to focus on a subject, recompose the frame since most subjects won’t appear directly behind the AF sensor. Now that you have focused on the subject and recomposed, the AF sensor may be far from the specific subject you want in focus. You have to push the Shutter button to take the photo and if you have Shutter AF-ON, it now refocuses on whatever the sensor is pointing at. By turning Shutter AF off you no longer have to worry about the camera refocusing AFTER you have focused on the subject you actually want.  In short, having both Back Button AF on and Shutter AF-ON, they fight each other and completely negate the benefit of either one. Let me now if this is as clear as mud. I’ll try it gain if needed. Hope this helps. Sorry for the long delay in answering this.

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There are 3 comments on this post…
  1. David RubensteinOn Aug. 15th, 2023 (8 months ago)

    My experience is the same as Richard Barbour’s. On my Lumix FZ300, the back button lock overrides the shutter button, which does not try to reset the focus.

  2. Richard BarbourOn May. 27th, 2017

    Thanks for the reply, but my G85 doesn’t work that way. When I set focus with the back button (I also have “Auto Lock Hold” set to ON) it stays that way no matter if I push the shutter half or all the way. It will not lose focus until I push the back button again. At that point I can use it again or use the half-shutter method.

    • Portrait of Daniel J. Cox

      Daniel J. CoxOn May. 27th, 2017

      Ok, sounds like an interesting setup. If it works for you that’s all that matters. I have to say it sounds confusing to me. But to each their own. Thanks for clarifying and joining the conversation.

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