Smooth transition between perspective and orthographic

Hi guys!

I would like to ask if any kind soul knows an easy way to achieve a smooth transition effect between camera perspective and orthographic modes, similar to that found in the Editor (when you click the upper right gizmo alternating ‘persp’ and other ortho modes).

How to do this when I use the game camera?

Thanks a lot!!

Same question here :

http://forum.unity3d.com/threads/32765-Smooth-transition-between-perspective-and-orthographic-modes

And also in the scripting section. Why?