Sigma 50-150mm lens: noisy when focusing

I have just acquired this lens, it seems to be focusing pretty accurately, but when it does so it isn't as quiet as my other sigma, the 85mm, or in fact any of my other lenses. To put it bluntly, it "chatters" once or twice as it is acquiring focus. If this is typical of the lens, fine, but I only have a few days to return it if it is abnormal. Any thoughts, people?

Which version of the lens do you have? If its the OS version then the "chatter" could be the stabilizer, which is far from quite.

It's the OS version, purchased new (ex-demo), definitely not the OS as it is only when focusing. I also tried it on AI-servo, and it's quite noisy!

Here are two quick videos.

First is AF with OS off and second if AF with OS on (the click at the beginning and end are the OS turning on and off and AF is nosier with OS on)

http://www.youtube.com …P2NngFEA&featur​e=youtu.be

http://www.youtube.com …tSGaj8-Y&feature=youtu.be

Also, the AF does kind of make a "chirpping" or "chatter" when it locks focus.....hard to explain it but it is normal.

Ha! Never occurred to me to look for videos of the lens. I have to say that the couple of videos of the lens actually locking focus sound a lot quieter than mine. The main problem is I will be using mine on AI-servo a lot of the time, and it's quite a distracting chattering noise as it keeps refocusing.
I'll try it out on a shoot tom, and see how distracting the noise is, but may well send it back, as it definitely doesn't sound quite normal. My 70-200 F4L is barely audible when in AI-servo.
Have been impressed with the photos it has produced whilst testing it, really don't want to have to send it back.

nephthysnick wrote in post #16707395
Have been impressed with the photos it has produced whilst testing it, really don't want to have to send it back.

Then don't. The "chattering" you're talking about is normal with this lens. I shot a hockey game last week with it and I can honestly say I never once noticed the AF sound. And if you think the AF is loud you must not have had the 70-200 f4 IS, good god that IS on that lens was loud!!

Oh, I agree, the IS is pretty loud, but not as loud as the 1st generation IS 75-300 I used to have, 10 yrs ago: that sounded like grinding gears. If you reckon the chattering is normal, I'll give it a good test tom.
Many thanks for the help.

I gave it a good test, and it worked great, got some striking images, brought the 1st one up in lightroom as my wife was walking behind me, and she went "oooh, nice!"

BUT

I went to use the lens the next day, and got a dead lens: "Err 01 camera lens communication failure" or something similar, so this morning it left on its journey back to the supplier. As soon as I have the refund, I'll be buying another copy, and should I take any pictures that I reckon are good enough for the forum, I'll post them.