[Jim Radcliffe]

Before I bought the DA* 16-50mm I had read that it was prone to SDM problems (as in failure) but I went ahead and bought it anyway.. It is a great lens and I use it quite often.

A few months ago I noticed that AF was becoming intermittent on it and at first I chalked it up to issues with low contrast focus points.. then it reached the point where I had to actually defocus the lens manually to get it to focus automatically. Then it reached a point where it just would not focus at all and off it went to C.R.l S. in Chandler, AZ.

Spoke with them this morning and it shipped on its return trip to me yesterday. I asked what the repair involved and they informed me that they replaced the SDM. Not unexpected.

Question: If you have had your SDM replaced on that particular lens in the last year or so, how has the lens performed since it was returned from repair? Has the SDM failed again since repair?

It seems the SDM is not quite up to the challenge of moving that much glass around and maybe a stronger SDM is needed for this lens. Your thoughts?

[Aegon]

Convert to screwdrive:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/208353-how-dea...m-f-2-8-a.html

Or sell it to me.

My 50-135mm had been in the shop 2 or maybe 3 times. "Fixing" the SDM wasn't a long-term solution. Converting to screwdrive was.

[RossCo]

I had my 16-50 fixed 2+ years ago and it has worked very well since. It is my go to lens and I have over 30,000 images on my K7 most of them with my fixed 16-50.

[Louicio]

Didn't they locate and fix the fault? I believe it was something as simple as a nut that would gradually tighten until it locked up the SDM motor.

[Rondec]

I had the SDM motor in my DA *16-50 replaced in October of 2009, about six months after I purchased the lens. It has worked fine since that time.

[Tom S.]

I recall reading in another post that Pentax changed the SDM motor last year, so if CRIS put in one of the new motors, you should be golden.