[PolishMike]

First of all, sorry for posting something that has been discussed many a time already. I have read every thread and review of the lenses in question I could find, and I'm hoping for some up-to-date advice.

After my trusty old K100D utterly failed me just when I needed it most on a trip to Guatemala, I decided it's time for an upgrade. Weighing up my options I had just decided to go for a Nikon D90, when Pentax announced their shiny, sexy new K-7.

Now I need to pick something to replace the kit lens (I have never been happy with the 18-55 kit. The DA 50-200 is however, a great lens for the price). Looking at the Nikon, the Tamron 17-50 f2.8 seemed like the obvious choice. Pentax, however, have got their DA* 16-50 f2.8 - which is not only wider but weather sealed and ultrasonic. (I don't mind spending the extra £100 if the Pentax is a better lens)

Now, I have seen some pretty scathing reviews of the lens, and if dpreview's forums are anything to go by I should give it a wide berth. Just the fact that there is a sticky here documenting faulty examples of this lens is pretty concerning. At the same time, I have seen some really nice photos taken with it and some people swear by it.

Is the reported low quality of the lens simply due to flaws in the early production runs, or is it just not a very good design? Are recently produced copies of the lens "safe" to buy, or do duds still happen fairly often? I'm having a hard time finding more recent tests of the 16-50 that might give an indication of the quality of the lenses currently produced.