Originally posted by PentaxPoke My testing disagrees with your opinion. So does that of the Photozone tests. The DA* 16-50 lens has very poor edge sharpness. Especially wide open. That might be fine for portraits where the softness is hidden in the bokeh, but that is it.
And mine with yours. None of these (Da* or Tammy) I tried was as sharp in the corners as let's say FA35 or DA14, but both were fine and da* seemed better in this respect.
But both these lenses do have variations. Ultra wide to normal zoom is perhaps the most challenging lens design. There are about 18 elements in each of them to align correctly. I guess it is difficult to get them right and to ensure they do stay in their exact position during usage and abuse.
And now to the point - let's say I'm in a camera shop and there are DA* and Tamron in front of me, both good copies and fine optically. I'm going to pay the extra for the build quality - and accept the fact that in-lens motors will eventually fail after few years.