how can i increase or decrease size of camera with control speed.

hello guys,
i am working on 2D game using orthographic camera.I am using the following code to decrease the size of camera.my object got zoom in perfectly,but i want to control the zoom in speed a bit slow instead of sudden.
please tell me how can i do that.

Code (csharp):

1.  
2. camera.orthographicSize=4.6;
3.  

 

Here's a quick way of doing a soft camera zoom:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class ZoomIn : MonoBehaviour {
5.  
6.     // Use this for initialization
7.     void Start ()
8.     {
9.         StartCoroutine(ZoomCamera(20, 5, 5, 100));
10.     }
11.  
12.     IEnumerator ZoomCamera(float from, float to, float time, float steps)
13.     {
14.         float f = 0;
15.  
16.         while (f <= 1)
17.         {
18.             Camera.main.orthographicSize = Mathf.Lerp(from, to, f);
19.  
20.             f += 1f/steps;
21.  
22.             yield return new WaitForSeconds(time/steps);
23.         }
24.     }
25. }

 

Thanks Sir