[Shall]

Just to say this worked for me on my 17-70mm.

[KonradB]

I got my stuck 16-50mm to work using the methods described in this thread. The only problem is that the lens is very sluggish, sometimes it works OK, then I will put the camera to one side, come back a few minutes later and the lens won't focus, I have to jab the AF button for ages before it works again. I found this so frustrating that I finally got round to converting the lens to screwdrive, so much more reliable thanSDM.

But thanks for all of the useful contributions here.

[mikeSF]

I don't believe it but it worked!!

My DA*55 failed and I was going to send it in for repair.
I happened across this thread just now and tried it and after about two minutes of holding the AF button down for about 3 seconds, it freed up and now it works. Thank you.

[mikeSF]

and then a year after my last post, my DA55 stopped focusing again. I tossed it back in the bag for a couple months, kinda forgetting there was a DIY fix...searched my way back to this very thread, held down the AF button several times and viola, back to life!

[vietnam74]

Read about this so I decided to re-enable my SDM again for both 16-50mm and 50-135mm DA* lens. Holding down the focus button alone fixed the 50-135mm right away and the 16-50mm wouldn't cooperate. Saw your note so I gave it a try and it's worked! Now get both lens focus with SDM motor again! The 50-135mm SDM motor is little noisier than the 16-50mm SDM motor.

SUCCESS!!!!

After doing as described for several minutes, I finally saw the lens come to life. IT'S ALIVE! But it was slow as molasses and not consistent. I kept at it, and then refined the process:

1. Set to AF.C
2. Put camera on table or lap and aim at distant object (~infinity or across the room)
3. Manually move focus to 1'
4. Press and hold AF button
5. As motor moves lens to infinity, manually move the focus back to 1'
6. Do this for several minutes, sometimes releasing AF and starting over
7. You can feel when the manual rotation to 1' would "catch" the AF motor as it tried to move to infinity, sometimes it felt like it would catch the motor and wind it the other way
8. Eventually, the AF motor got faster as it moved to infinity

I then reversed the exercise, focusing on a near object, manually moving the AF to infinity, and then pressing AF, working against the motor as it tried to move to 1'.

The 16-50 went from molasses to maple syrup to olive oil in a matter of minutes. I imagine if I do it for another hour or so it would become a Canon L-lens!

Thanks OP! My hero!

[UncleVanya]

Read about this so I decided to re-enable my SDM again for both 16-50mm and 50-135mm DA* lens. Holding down the focus button alone fixed the 50-135mm right away and the 16-50mm wouldn't cooperate. Saw your note so I gave it a try and it's worked! Now get both lens focus with SDM motor again! The 50-135mm SDM motor is little noisier than the 16-50mm SDM motor.

I have worked on lenses that had reduced focus accuracy and still worked in SDM but when converted they focused much better. Be on the lookout and make sure that your SDM is working as well as your screw drive was. I am happy to hear it worked that's an interesting approach. It directly address the possible stickiness in the system which has been discussed.

[vietnam74]

I've converted them to screw drive a while back after SDM replacement and still failed. However, they're kind of noisy when focus. I did not aware of this option to bring back the SDM motor from stuck so it's great experiment for me just to play around with these lens.

[Belnan]

Hey guys, I found another cheap way to quick fix the SDM problem. You just hold the AF button down for a couple of seconds and let go, then you hold the AF button down for a couple of seconds and let go, repeat, repeat, and repeat until it starts to move and focus again.

I actually just got a second 16-50 and did something very similar. I could hear the motor trying to do something so I kept trying to make little af adjustments. And then after a couple minutes it moved a little tiny bit and looked focus. Then I just kept at it and like being awoke from death it now seems to work like a charm. I was going to convert to screw drive but that seems like a waste now. So excited it came to life.
Btw I believe the previous user let it sit for some time.

[LarsGeisler]

Just to confirm. This worked for my DA* 55mm SDM. I put it on yesterday and noticed it hardly worked, and then stopped working outside. I hadn't used it for a long time - couple of years. It seems like these lenses have the motto: Use it or loose it.

[JohnX]

Old thread, but same experience.

DA*300. Wouldn't focus. Tried hitting the AF button multiple times. No success.

Set the lens to manual focus and operated the focus from end to end half a dozen times using a screwdriver in the screw-drive slot Lens felt freer each time it went from end to end.

Went back to the AF button and the lens operated right away.

Certainly seems to me that the SDM is underpowered to overcome the stiction of a the lens that has not been used in a while.