public void setFocusRange(float f) {
        this.focusRange = f;
        if (material != null) {
            material.setFloat("FocusRange", focusRange);
        }

    }
Sets the range to either side of focusDistance where the
 objects go gradually out of focus.  Less than focusDistance - focusRange
 and greater than focusDistance + focusRange, objects are maximally "blurred".

@param f the desired half extent (in world units, default=10)
jme3-effects/src/main/java/com/jme3/post/filters/DepthOfFieldFilter.java