Depth Of Field Target vs WorldFocusDistance

[gandarufu]

Hi all,
I have a hard time understanding the target value of the DOF-effect of r3f Drei.

If I calculate the distance from the camera to the target object in world coordinates in the useFrame() hook and pass it as WorldFocusDistance to the component via a state variable, the DOF works as intended.

  const worldTarget = new THREE.Vector3();
  const worldCam = new THREE.Vector3();
  const [distance, setDistance] = useState(0.0);
  
  useFrame(() => {
    dofTarget.current.getWorldPosition(worldTarget);   // ref to target object
    dofCam.current.getWorldPosition(worldCam);         // ref to camera

    setDistance(worldCam.z - worldTarget.z);
  });
  
<EffectComposer disableNormalPass>
  <DepthOfField worldFocusDistance={distance} bokehScale={6}/>
</EffectComposer>

Trying to achieve the same result with the target property, doesn't achieve any usable results.

const targetPos = new THREE.Vector3(0, 0, 0);
useFrame(() => {
    targetPos.copy(dofTarget.current.position);
    dofRef.current.target = targetPos;
  });

<EffectComposer disableNormalPass>
  <DepthOfField  ref={dofRef}  target={targetPos} bokehScale={6}/>
</EffectComposer>

I am sure that using the built-in target route would be more performant, but I cannot figure out how to use it correctly on my own. Any help would be appreciated.