Originally posted by PentaxPoke ...
I am so frustrated with SDM lenses. Five bad copies now (3x DA* 16-50, and 2xDA* 50-135) ALL my other Pentax glass (non SDM) has been flawless since the 1980's.
Wow, can't blame you, I'd be too if that happened to me. I'm a big DA Ltd fan, so there's little SDM in my inventory and I only have one SDM Lense, the DA*300, which has showns some intermitent failure but never failed totally on me. I wish it would if it is going to die anytime soon as I only have a few more months of warranty left and sending a perfectly working lens now to Pentax is a waste of time and money. I have to admit that I am no big fan of AF altogether, especially if it's going to be in the lens, any lens, any brand. With stablization in lenses in addition to SDM (non Pentax that is), it's just more things that can go wrong, so switching system is no guaranty of reliability or longevity for that matter. I can't affort most quality modern MF lenses (eg Zeiss), and accurate visual MF is difficult at best on APS-C size viewfinders (not to mention innacurate in the case of my K10D, I can't speak for the K7), so fixing failing AF SDM lenses is I guess still the cheaper alternative in the long run, albeit frustrating I'll admit.