Help with Sigma lens

[Dezmo]

So recently I picked up a 50-200mm F4-5.6 DC OS HSM (made by Sigma). While toying around with it one day I noticed that it sounded like an element was loose whenever the lens was manipulated, rotated or even lightly shaken. I brought it back and the store told me that everything was fine with the lens. Has anyone had any experience with something like this? Thanks for any help.

[dcclark]

What is the sound? Can you describe it?

Most lenses do make some sort of sound when you shake them. I usually hear a slight clicking or tapping sound in mine. This is usually because the movable elements (zoom lenses have many moving parts!) have a tiny bit of play in them.

[Dezmo]

Originally Posted by dcclark

What is the sound? Can you describe it?

Most lenses do make some sort of sound when you shake them. I usually hear a slight clicking or tapping sound in mine. This is usually because the movable elements (zoom lenses have many moving parts!) have a tiny bit of play in them.

It's kind of like a "clunking/knocking" noise (hard to describe). You can even feel it knocking around.

[inkista]

Are you sure it's not the camera's orientation sensor you hear?

[dcclark]

I just noticed that the lens is OS -- stabilization systems often make a shaking noise. There are one or two lens elements which move around, to stabilize the image. They are normally locked when the lens isn't actively stabilizing, but it is possible that they are moving in yours.

[Dezmo]

Originally Posted by inkista

Are you sure it's not the camera's orientation sensor you hear?

Still makes the noise when the lens is detached from the camera body

Originally Posted by dcclark

I just noticed that the lens is OS -- stabilization systems often make a shaking noise. There are one or two lens elements which move around, to stabilize the image. They are normally locked when the lens isn't actively stabilizing, but it is possible that they are moving in yours.

that sounds very plausible. With this in mind, I re-attached the lens to the body, pressed the shutter button half-way (until the OS activated) and gently shook the camera... this time no knocking noise. I think it is the OS.