http://forum.unity3d.com/threads/dynamic-depth-of-field.58828/

gistfile1.txt

using UnityEngine;
using System.Collections;
 
public class DynamicDOF : MonoBehaviour {
 
    public Transform Origin;
    public Transform target;
    public DepthOfField34 DOF34;
   
    void Update () {
   
        Ray ray = new Ray(Origin.position, Origin.forward);
        RaycastHit hit = new RaycastHit ();
       
        if (Physics.Raycast (ray, out hit, Mathf.Infinity))
        {
            DOF34.objectFocus = target;
            target.transform.position = hit.point;
        }
        else
        {
        DOF34.objectFocus = null;
        }
       
    }
}