A quick back button auto focus setup guide up for @Wes
I don’t have the same camera but the process and menus should be very close.
We’ll start by setting up your default AF settings.
Go into your menu and select the AF menu. The first tab should look something like this:
Set AF operation to SERVO AF. You shouldn’t really need ONE SHOT AF - in situations where I could use it I always end up using manual focus.
AF method should be set to your preferred method.
Subject to detect - as required.
Note that Eye detection is greyed out and set to Disable. This is only because by default I am not in subject tracking, the way it is set up, it will work by simply pressing the AF-ON button without constantly going into the menu and enabling it. But you might have to temporarily switch to EYE AF via the quick menu and enable it once after you have everything else set up.
Continous AF - Disable. The naming on this one is a bit confusing. Having it enabled simply means that your AF will always try to focus on something which can quickly drain the battery and is simply not needed the way I have my AF set up.
Touch & drag AF settings as desired.
Set Inital Servo AF pt for subject tracking as required. I have it set so that it tries to find something to track around the area where I have my AF point when I activate EYE AF
There are more options hidden within the other submenus but these are the most important aspects.
Next up we need to customize some buttons:
First, lets decouple AF from your Shutter button and set the half press to Metering start only.
Next, scroll down, and select the AF-ON button. Set it to Metering and AF start and press INFO to set up the details. This is where the magic happens.
Set AF operation to SERVO and AF method to subject tracking with face/eye detect. You can even set the different AF cases for your servo AF but I don’t want the button to overwrite my AF case settings so I have it disabled.
Do the same for your *-Button but this time, instead of setting it to subject detect, simply leave the detailed settings disabled. This way it uses whatever AF operation and AF method you have currently selected to focus.
That’s basically it. It also doesn’t matter which button you use for subject tracking and which one you use for simply activating the AF.
There are of course a lot more options that modify your auto focus’ behaviour that I have also customized but this is very situational and you need to find out what works best for you.