Originally posted by JerryFu I've just started experiencing this problem in my DA* 50-135. I last used the lens maybe 2 months ago...and when I took it out over the weekend, no autofocus. I think I eliminated all other possibilities, and only after my lens stopped working did I find out there was an issue with the DA* 50-135...
I bought my lens brand new in August 2009, so I should be under warranty still, but I haven't talked to Pentax yet.
Sorry to see my old thread resurrected because of another unfortunate victim. You have experienced "
Sometimes
Doesn't
Move." The only consolation I can give you is that at least it didn't happen to you at a once in a lifetime event (like it did to me.)
Did you notice if you can "wake" the SDM back up by turning the focus and zoom rings, or taking off and replacing the lens, etc?
Eventually the SDM may fail completely like my first one did, after exhibiting this for a while, so you will definitely want to take action so you don't end up with a $1000 MF lens. I recommend the following:
1) Write down the serial number of the lens you have now so you can compare with whatever they send you back.
2) Contact Pentax service (you can do so via email) I think they are reasonably responsive, and you should get a reply in a couple of days. Clearly state the problem in detail, and that you are having intermittent SDM failure. Make sure that they know that sometimes it works, and sometimes it doesn't and you have tested it many different ways. The reason is that if you send it to them, it may choose to work. They send it back to you with a "no service needed" and then it fails later. Also print out the detailed description, and include it in the box you send them with the lens.
3) I was too mad to think of this at the time, but I wish I would have taken video tape of the SDM working intermittently, and then me "waking it up." Is there any way you can do that and post to Youtube or something? It might be useful to others, or Pentax to diagnose for the future.
Good luck.
In case anyone was following this old thread, it was started when my first DA* 50-135 was having problems. When I got my second one, and it started having SDM problems, this thread continued here:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/81128-more-sup...-problems.html