Originally posted by robert52
Thanks for that 1 lens I was looking at 50 /135 lens 2nd hand
This is a great lens by all means and is Screw Driver convertible. Besides.. the SDM failures albiet true can come back to life once heavily used. I have about 3 DA*s that show the wake up issue. Once up they work very well. It seems the tolerances with these SDM motors was so tight that any over torqued assembly of these motors on the lens ended up having trouble with failure like symptoms (atleast that is my observation).
I have seen comments on the forum around the motor mount screw being too stiff and once wriggled gives motor a chance to rotate bringing back that seemingly dead SDM to life. I have not tried that myself.. but the more I use the SDM the more it seems to be freeing up. I have one 50-135 that came back to life when I used that on my K-01 that refused to wake up. I made it focus on a wall that did not have much contrast in it making the focus motor run end to end seeking focus. It did heat up quiet a bit when I did that (out of frustration..) but it came back to life again. I was almost going to burn it out but the battery depleted just in time so I guess it survived the abuse.
These motors also show some temperature sensitivity (as in very hard to get them out of slumber in winter vs in summer). Once woken up they behave normally. The screw drive conversion of course bypasses this SDM and brings back the lens to life with no problems whatsoever (except the noisy gear drive).