AF Limiter lets you choose the range of distances over which autofocus operates. Limiting the autofocus operation range helps shorten the time needed for autofocus.
When the focus shifts from the subject to the background or other object, it takes time for the camera to refocus on the subject. Setting [AF Limiter] helps prevent drastic changes in focus when you are unable to keep the AF target positioned over the subject.
You can also use it to prevent the camera focusing on foreground objects when shooting through a fence, window, or the like.