New 18-135 STM Lens Click like noise on turning zoom ring

[rnaghdi]

I recently have purchased a Canon 70D with 18-135 STM Lens Kit.

I have noticed that there is a faint repeating click like noise (like tik tak of wrist watch) when I turning Zoom ring.

turning the zoom ring when camera is off, there is not any noise like that.

I want to know whether it is a normal or there is something wrong with my new lens or camera.

[MikeSowsun]

My guess is you are hearing the aperture blades changing as you zoom.  Try zooming the lens when it is removed from the camera.  I bet you won't hear it then. 

[rnaghdi]

Thank you for kind attention. Your comment was so helpful for me. When camera is off there no sound like that.