Originally posted by Rondec The DA 16-50 is a decent lens. As to whether or not it is better than the competition in this focal length I can't say. It is certainly faster to focus than the 50-135 which struggles mightly in many situations, mainly because of a long focus throw. I think Falconeye is right however, I see Pentax continuing the 16-50 in production, but not changing the design. They had enough trouble taking care of the decentering problems with it. I had my SDM changed on it awhile back and it does seem more reliable (although not faster to focus).
It's not about whether 16-50 is focusing faster than competitor or 50-135, it's about the SDM compared to screw drive, and the failure.
If there has been failure of the SDM as whatever design or quality defect, pentax needs to tell us it's been solved. neither Saying"we had issue but we fixed it" or being silent is a good idea. the best way is to develop a gen2 lens, says improved motor (DC?). then we will know it's fixed, and pentax is not embarrassed.