“Back Button Focusing” refers to a way to engage autofocus (AF) on your camera separately from the shutter button. In practice, it allows you to use AF and then automatically fall back to MF to be able to expose, compose, and shoot without worrying about the focus changing when you actually shoot. Personally, I don’t always want to shoot this way … I may want to have everything (focus, exposure, and shot) happen quickly with a simple press of the shutter button. But for those times I do want this, here’s how I set up the E-M5.
There are many ways to set up the various customizable buttons on the E-M5, so please just consider this as a guide. This is just how I do it and I’m sure many of you will find different setups may work better for you.
First, I go into Custom Setup (Gear icon) > AF/MF > AEL/AFL where I set the modes for focusing to S1/C2/M3. The numbers refer to different modes, which in this case means Mode 1 for single AF which enables the shutter button to do AEL/AFL. Mode 2 for Continuous AF, starts focus at a half press and locks exposure and focus when the shot is taken. Then Mode 3 for MF sets the shutter button to AEL when half pressed and then takes the shot when fully depressed.
The next step is to assign buttons for focusing and for switching between AF and MF. So get back into the menus, Custom Setup (Gear icon) > Button/Dial > Button Function. Once there, I set Fn1 Function to MF and Fn2 Function to AEL/AFL. And that’s it! 🙂
Now, when I’m in MF, I just press the Fn2 Button to autofocus (after which the camera is still in MF) and then compose and take the shot. So the camera stays in MF, but momentarily switches to AF when the Fn2 Button is pressed. The beauty of this is that if you need to tweak the focus, a small twist of the focus ring takes care of it. Very nice!
If for whatever reason I decide to have it all happen with the shutter button, I just press Fn2 and the camera switches into S-AF and stays there until I change it. I would use this in more fluid situations like street shooting or maybe candids of the grandkids when I don’t want them to pose but rather try to catch them “in action”.
I’ve written previous posts about setting up the E-M5 (Customizing the Olympus OM-D E-M5), but of course that’s always a work in progress as you learn more about any camera. Also, as you move from one project to another, your requirements may change, so flexibility is the word of the day. 🙂 However, to be able to be flexible and make the changes to your cameras setup as necessary, you must also have a thorough knowledge of what your camera is capable of and how to take advantage of those capabilities.