Originally posted by rwfarnell I am considering buying a new lens for a general walk around lens to go with my K5.
Pentax 18-55 kit lens
Pentax 55-300
Tamron 70-200 f2.8 (gets used the most)
Let me try something else than the others have; I do not see a lot of advantage for you in getting the DA18-135 as it overlaps both the 55-300 as well as the 70-200 in at least some of their range - these are quite formidable lenses and I doubt the 18-135mm will trump their IQ at any setting between 55 and 135. It's had quite mixed reviews.
Pain point seems to be the 18-55 kit lens - its IQ nothing to really write home about, its range somewhat limiting. If you'd get like a DA17-70 or the Sigma equivalent(s) (both HSM and the older version), you'd have more range and heaps of IQ. Slots in nicely under the Tammy you have, with the 55-300mm doing service when you know you need the long end.
The 17-70's serve you well for interior and street candids, as well as being a nice portrait range. The older Sigma (f2.8-4.5) has lovely bokeh to boot AND does extreme close-ups as well!
Save you some bucks AND improve your overall quality impact - how does that sound?