Strange sound- D500 + Sigma C 150-600

I borrowed a Sigma 150-600 contemporary to try with my Nikon D500, and was using it with image stabilization on (center notch). I had it resting on a skimmer sack on my car window. It started making a whirring sound and it was vibrating. Rather disconcerting!  Is that what happens when the camera/lens are stable or on a tripod? I turned the IS off and it seemed to stop. Never had that happen with any other lens or camera. The Skimmer sack is fairly soft- didn't think it was really stable.  And this is not the first time Ive used this camera and lens with it.  Didn't happen before with the IS on....

Any thoughts out there?


Thanks!

I just put my Sigma 150-600 Sport on my D500 on a totally stable surface and it did not exhibit that behavior. In a quiet room I actually had to put my ear to the lens in either OS mode to hear the OS motor and there was absolutely no chatter of any kind. Now if you are on a subject that isn't perfectly 100% still like a bird and your camera isn't 100% still and it wouldn't be on a bean bag, the continuous AF system will make constant minute adjustments and that is totally normal.

E.J. Peiker wrote:I just put my Sigma 150-600 Sport on my D500 on a totally stable surface and it did not exhibit that behavior.  In a quiet room I actually had to put my ear to the lens in either OS mode to hear the OS motor and there was absolutely no chatter of any kind.  Now if you are on a subject that isn't perfectly 100% still like a bird and your camera isn't 100% still and it wouldn't be on a bean bag, the continuous AF system will make constant minute adjustments and that is totally normal.

Thanks E.J. This was way beyond constant adjustments. The whirring sound was MUCH louder than what I can normally hear, and the whole camera and lens were vibrating.  There would have been no way a picture could be taken. I wish I knew what Sigma meant by "chatter". I will probably send the lens back to B&H as defective.  (I actually bought it, thinking I'd like to try it, and I DO like it.)  Debating whether to just get a replacement or go for the new Tamron 150-600. Reading in the forum, doesn't look like that lens is well favored.

(Here's a quote under "ABOUT OS FEATURES"

"If the camera is turned off or lens is detached while the Optical Stabilizer function is in operation, the lens may emit a chattering noise, but this is not a malfunction."

I'm not sure what that means , or whether it includes a vibrating camera and lens.

It's the old Tamron that isn't favored. I haven't used the G2 but by all accounts it is much improved.

As for the Features comment, that just means if you disconnect the lens while the OS is still spinning, it could make a clunking sound when you detach the lens.

E.J. Peiker wrote:It's the old Tamron that isn't favored.  I haven't used the G2 but by all accounts it is much improved.

As for the Features comment, that just means if you disconnect the lens while the OS is still spinning, it could make a clunking sound when you detach the lens.

Hmmm- so the sound and shake I experienced is totally different...

As for the Tamron, I was referring to this discussion:

viewtopic.php?f=57&t=265533&hilit=Tamron+150+600

But that was quite a while ago.  The Tamron is quite a bit more expensive too.