smc DA* 16-50mm Focus Issue

This sounds just like the problem I had with my first DA*16-50 and I think my 3rd is going the same way.

The first one, on a K10D was very sticky. The auto focus would just move a little bit and then stop. Manually moving it several times, or putting it on a non-SDM body (I used a k100D) and doing some end-to-end focusing would un-stick it and then it would work fine for a couple of days. After a month or so of this I got to the point where I could not trust it so sent it back and got a replacement.

I'm now on my third DA*16-50 and using a K-7. This one is also causing similar problems. It seemed to start with an earlier firmware upgrade to the K-7. Often the auto focus does not move and also, occasionally, the K-7 does not light or flash the focus hexagon in the view finder. Other times the the lens does not move and the hexagon will flash to indicate that the focus has failed.

To get it going I often put the lens cap back on, manually set the focus to minimum distance (0.3M) and then try some auto focusing. The lens should swing from min to infinity focus and and come in a little. It seems to take a few attempts to unstick the lens focus and then it seems to be fine for a few days.

I'm not completely convinced what the problem is with this 3rd lens. Sometimes when it sticks without flashing the focus hexagon I point it at a bright, hi contrast, subject and it all comes good. I therefore think that there may be 2 separate issues, sticky focus motor, and some issues with the K-7 firmware and that the two can interact.

I still have a few months guarantee on this lens so I'm just waiting to see if it gets any worse. Certainly with the first one it took some convincing to get a replacement as once it was unstuck it would be fine for a couple days.

Hopefully yours is still under guarantee. My recommendation would be to try the test with the lens cap on to prove that it is a sticky SDM and get it replaced or fixed.

My experience with these lenses has put me off buying any other SDM lenses. I don't have confidence that they will have the longevity of the older screw-drive lenses. While I know you can probably get them fixed I just don't want the hassle.

Glyn