Sigma AF hunting issue.

Has anyone else here got a Sigma 17-50 f2.8 EX DC OS?

I had one delivered today and the AF just hunts, and hunts, and hunts! Occasionally it focuses, mostly at 17mm, but anything above that. It just will not focus!

Tried on both my K5 and K3.... same results on both bodies. Tried all focusing modes. Still no joy.... Also tried with the OS on/off, and body stabilisation on/off....

Has anyone else had an issue with this lens?

I've had the same lens for over 15 years and not had any issues,

Have you tried the usual default option of cleaning ( ideally with Isopropyl Alcohol ) both the lens contacts inc the complete mount as well as the camera mounts / contacts ?

Thanks Chris, I'll give that a try.

Last Thursday I notice the same problem on a Sony /Tamron combination.

A few quick tests showed it was over F8 when the problem arose.

Further checks showed the problem was there with two out of three bodies (the oldest ones)

So back to the original combo and changed the AF setting from C to S and it was fine.

I can live with single shot AF.

It looks like you have tried most of the above apart from F stops,

It might be worth a try



John

Update....

I think the lens is defective. The first HSM lens I have had that has failed! Usually they're great....

I noticed a sticker on the box that has a circled D on it. I'm wondering if that could be a grading system, like some retailers of used kit use to grade the quality of kit?

I bought it from a charity, who had not tested it. Nor had they indicated it was untested on their ad. If it had been marked untested, I wouldn't have bought it. It will be getting returned for a full refund.