This switch, found on selected Sigma telephoto lenses, allows users to limit the focusing range to either near distance or far distance. This helps speed up AF, and also ensures the camera won’t attempt to focus on an unwanted area of the frame. For example, when photographing zoo animals through a wire fence a photographer could set the focus limiter to, say, 10m–infinity, to stop the camera continually trying to focus on the fence, which is nearer to the camera than the subject. On some Sigma L-Mount lenses, the distances on the limiter can be customised via the USB Dock.