Originally posted by FantasticMrFox I was also wondering what the star lens will be, but then I realised there is nothing on the road map. So maybe this is just it (for the foreseeable future)?
IMO, this is a placeholder lens. At some point I expect to see a DFA* 24-70 f2.8 with aerobright II coatings. But Pentax doesn't have the resources to make that lens now. Maybe in three, four, five years they can manage it.
Keep in mind that the Tamron 24-70 is a very good lens. The Canon and Nikon 24-70s are reputed to be better, but the differences, particularly in terms of sharpness, are too slight to be significant. The main difference, in terms of practical output, is a richer tonal signature in the Canon and Nikon OEM standards, but the Pentax HD coatings could very well be a difference maker here.
The Tamron 15-30 is reputed to be even better. Some claim it's as good as the Nikkor 14-24. I don't happen to believe that's true (the Nikkor has richer color rendition), but again, adding Pentax's HD coatings could take this lens to the next level and allow it to hold it's own with the highly regarded Nikkor.