I don't know if you'll find this useful, but when you set the X-T1 in M mode (focus mode selector) and the clutch mecanism in AF position, obviously you cannot manual focus using the lens, but the camera
works as in manual focus, and the AF-L button works to focus. Indeed, in this configuration, this is the only way to focus: the shutter button don't change the focus when pressed. It may be useful, for example, in situations that
you focus once and don't want to change the focus for the next shots. Maybe there are other uses for this configuration.