[geezer52]

I have a Sigma 18-250 DC Macro lens that I've owned for about two years and taken thousands of pictures with. Used mostly on my K30, I've sometimes taken hundreds of pictures with this lens in a day. I love this lens as it has served my needs very well taking action shots using continuous focus and stills at all focal lengths in various lighting conditions. It has been very reliable but lately I've noticed an odd problem sometimes when it tries to gain focus. It will bring the subject into near focus and then I hear the lens motor chatter as it tries to find exact focus. But focus never locks on. If I'm shooting a still I can usually get focus to lock if I can find a high contrast edge near my desired point, But much more difficult for moving subjects. Lighting conditions when this happens can vary. Though somewhat oddly the lens still works very well if the camera uses the focus assist light. The lens behaves the same whether on either of my K30s or my K5. my So is a sign my lens is starting to wear out?

[vonBaloney]

I have a Sigma 18-250 DC Macro lens that I've owned for about two years and taken thousands of pictures with. Used mostly on my K30, I've sometimes taken hundreds of pictures with this lens in a day. I love this lens as it has served my needs very well taking action shots using continuous focus and stills at all focal lengths in various lighting conditions. It has been very reliable but lately I've noticed an odd problem sometimes when it tries to gain focus. It will bring the subject into near focus and then I hear the lens motor chatter as it tries to find exact focus. But focus never locks on. If I'm shooting a still I can usually get focus to lock if I can find a high contrast edge near my desired point, But much more difficult for moving subjects. Lighting conditions when this happens can vary. Though somewhat oddly the lens still works very well if the camera uses the focus assist light. The lens behaves the same whether on either of my K30s or my K5. my So is a sign my lens is starting to wear out?

Yeah, if behavior has changed for the worse on two different bodies, then maybe something loose or the motor starting to go. Might be worth it to send to Sigma for repair. (Sigma has also been known to accept trade-ins on lenses they no longer repair or that aren't worth it towards purchase of new lens at a discount.) My experiences with Sigma New York have been excellent...