Originally posted by sunshine7913 I'm not talking about the price. I'm complain about Pentax. Why can't they make their own?
You have got a number of varying quality answers already, but i think i might add another answer/reason. It would bind up Pentax R&D people and money that now can be used for other lenses and features.
Personally I think this is a good solution for customers as we get a high quality lens at a very nice price compared to what the price might be with a Pentax design. We also get it at the right time (compared to maybe after the FF launch). We already know from Tamron reviews that its a high quality modern design lens with high reliability (no production problems, oli spots, light leakages, focus motor fails or other problems). A very unmeasurable advantage is that we might see some other exiting products as a result from the R&D money/people.