Constant Noise from 24-70 F4 L (even when NOT focusing)

[Troutwink]

Hello-

I turned my camera on this morning and there is a constant 'gear' type noise occuring with my 24-70 F4 L.  It is occuring on both my bodies; 5D iii and 70D. Here are some supporting details. These pertain to both bodies as I tried on both.

1) Even with the Camera off, the noise happens once when I attach the lens. With the camera off, it just happens once, briefly,  when I put on the lens.

2) When I turn the camera on the noise starts and does not stop.  It is quite audible.  Much more than any "normal" lens noise.  It starts right away and does not stop.  Only turning off the camera will stop it.

3) I tried turning both IS and AF on and off, did not make a difference

4) I was able to take shots and the AF seems to be working properly.

Any thoughts?

Thanks so much in advance for your insight.

Regards

[Waddizzle]

Good info.  Which body are you using in the your four cases?

[Troutwink]

Hi Waddizzle-

Thanks for responding.  The same scenarios with both bodies (5D iii and 70D).  It was the first thing I tried to isolate whether it was the lens or the body.  

[RobertTheFat]

I guess maybe I'd suspect a short circuit in the IS mechanism. Almost the only other possibility left would be some kind of malfunction in the mechanism that keeps the diaphragm open to full aperture. In any case, it doesn't sound amenable to a DIY fix.

[ebiggs1]

Strange noises from an IS lens is almost always the IS.  It is not a DIY so call Canon service tomorrow.