If you're using your camera regularly, then the button position becomes a matter of muscle memory. I turn my camera on and off with my forefinger without even being aware of doing it. By the time the camera gets to my eye, it's on and ready to shoot.

When I first started back-button focusing, I couldn't imagine getting used to this new way of working. I'd been using the shutter button for as long as I'd owned an autofocus camera. But we adapt quickly, after a few days, it was second nature. On my Fujifilm cameras, I use the AF-L button for focusing, my thumb sits against the 'thumb rest', and the button is right there. 

This is all good until I fit the battery grip and turn the camera vertically. As you can see, there is an equivalent thumb rest on the vertical grip. But for some reason, known only to themselves, Fujifilm decided not to put the AF-L button in the same position, it's moved way over to the left. 

Now, I'm a simple guy with a simple thumb, and we've both got used to thumb rest/button position. If you start giving me thumb rest/button sometimes and not others, then my thumb doesn't have a clue what's going on. I start thinking about where the button is, where my thumb is – not what's going on in front of me.

Hence, ladies and gentlemen, I give you the Fuji thumb rest/button-guide, snappy huh! Ok, maybe not. However, it does work. I put my thumb against the thumb rest, but the guide says, "hold on there fella" and reminds my thumb to head west. I admit this isn't as good as having the button in the 'correct' position, but it's far better than it was before.

Using Sugru I've added the guides to the battery grips on both my XT-2 and XT-3; so far I'm happy with them. If you're a Fuji back-button focuser give it a go, it could be just what your thumb needs.

Mapping Fuji buttons for back-button focus.

As always, let's be careful out there.