[MikeyBugs95]

Used Photo Pro offers 6 month warranties. Did you buy it "as is "
with non working AF?

I forgot how it was described and now the listing isn't available. But when I received it, the AF didn't work.

[RayeR]

I wonder that nobody for the years have found some suitable SDM replacement part. ebay is full of cheap SWMs for nikon but I'm hunting hours and hours over Internet and simply nothing. I also wonder if that SDM was developed specially by pentax or if it is some 3rd company product that we just don't know about. There migt be a small chance to use nikon's micro SWM but I still unable got an answer from sellers what are mechanical dimensions of the motor so I don't know if it could fit inside pentax lens.

[labidas]

I wonder that nobody for the years have found some suitable SDM replacement part. ebay is full of cheap SWMs for nikon but I'm hunting hours and hours over Internet and simply nothing. I also wonder if that SDM was developed specially by pentax or if it is some 3rd company product that we just don't know about. There migt be a small chance to use nikon's micro SWM but I still unable got an answer from sellers what are mechanical dimensions of the motor so I don't know if it could fit inside pentax lens.[COLOR="Silver"]

I was just about to look on eBay. My SDM is kinda fishy and I don't think turning it (again) will make it any better. It sometimes fails to lock focus, keeps jumping around the focus point back and forth in tiny increments.

[UncleVanya]

I was just about to look on eBay. My SDM is kinda fishy and I don't think turning it (again) will make it any better. It sometimes fails to lock focus, keeps jumping around the focus point back and forth in tiny increments.

If you have one of the 4 that can be converted that's another option. (16-50, 50-135, 200, 300)

[stanwi3]

Do you think you could have given the motor the required "massage" by turning the screwdrive slot on the lens?

Yes, I believe I have fixed my SMC Pentax DA* 300mm ED (IF) SDM lens by just turning the screwdrive screw on the back of the lens. My lens was locked near infinity and AF would not move it; and I could not move it manually, either. After reading this thread, I cleaned the AF contact points on the lens and in the camera (K-1) and used a screw driver to focus the lens out to infinity and back to minimum focus a couple times (back and forth and back and forth). It is night time, now, so I could only try the lens in the hose, but it appears to operate (at least between 5 feet and 14 feet). I'll test it outside tomorrow and add further comments.

[stanwi3]

Ok, I had a chance to check out the DA* 300mm lens in the daylight today, and it works great. Only time will tell if this is a long-term fix, but I'll take it, right now.

By the way, it may be helpful to know what I was doing when the lock up occurred. I was shooting birds at a lake and noticed some barn swallows lining up on the electric wire right over my head. So, I started shooting straight up at them. After a few successful shots, the lens locked up. My conclusion, now, is that I missed focusing on the birds at some point and the lens went to infinity to seek the cloudless sky.

[thechumpen]

This article is still bringing joy! My 50-135 has not been used for a few years and had seized up. I found this and it is now working again, thank you!

It seems slower and sounds a bit “gravelly” still, but is working at least. Hopefully it will loosen up more with time.

[stanwi3]

Great! Always like to hear success stories.