unity - camera transform, rotate, movement follow a ball

using UnityEngine;
using System.Collections;

public class BallCamera : MonoBehaviour
{ 
    public Transform target;   //needed to drag a rigidboady to target

    public float relativeHeigth = 10.0f;

    public float zDistance = 5.0f;
    //×èÄáËÙ¶È
    public float dampSpeed = 2;

    void Update()
    {

        Vector3 newPos = target.position + new Vector3(0, relativeHeigth, -zDistance);

        transform.position = Vector3.Lerp(transform.position, newPos, Time.deltaTime * dampSpeed);
    }
}

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FOrum about camera movement
http://forum.unity3d.com/threads/wow-camera-movement.16949/