Difference between ae/af lock button and half press shutter button.

Dec 11, 2013
New Jersey (South) and Northeast Pennsylvania
Real Name
I have always been confused by the af/ae lock button. If someone can explain the nuances, it would be greatly appreciated.

My question is: Why would one press the af/ae lock button when the shutter button could do the same thing on a focus, recompose. I understand why one would set the button to lock ae only, but I just can't seem to grasp why it would ever be used to lock ae/af or just af.

Is the purpose for the ae/af for something other than focus/recompose?

Thanks in advance for your advice.

T N Args

Agent Photocateur
Dec 3, 2013
Adelaide, Australia
Real Name
call me Arg
You can lock the AF while you take a string of successive photos with the key subject all over the frame. That's very handy. In fact you can set the AF button to lock focus and stay locked while you release the AE/AF button, take as many shots as you need, then press AE/AF again to release focus.


Mu-43 Top Veteran
May 28, 2012
San Angelo TX
Real Name
Bruce Foreman
If you set the AE/AF button to autofocus and lock AF, it also switches to MF. With MF ASSIST set to ON, and the MF ASSIST function assigned to the lens focusing ring, the magnified assist "kicks in" as soon as you start turning the focus ring on the lens. A half press on the shutter release clears the magnified view back to normal view

It remains in this MF mode shot after shot (and video take after video take) until as you point out another press of the AE/AF button clears autofocus back to default half press of the shutter button.

The best of both AF and MF from one button.

I have my GX7, GH3s, and GH4 all configured this way. It also worked almost the same on the GX1 I just gave to my grandson.


Mu-43 All-Pro
Mar 4, 2014
Boulder, CO
- recomposing is not suitable when camera is set on tripod.
- for panoramas you want both focus and exposure remain the same over all tiles.
- lesser shutter lag

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