This is a lens I'm considering purchasingfor my K100after seeing it mentioned on some of the photography boards. How would the IQ compare to my DA 50-200? I currently have the 18-55 and 50-200 and I'm considering getting either the Sigma 17-70 and Tamron 70-300 as a replacement combination orthe Tamron 18-250 so I would have just a single walkaround lens but I'm not certain I want to sacrifice my 50-200. Any disadvantages of the 70-300 over the 50-200 other than weight and size?
I found using the Tamron 1.4 x TC on the Tamron zoom a very good combo that goes out to 420mm while it is only about 280mm on the 50-200 at long end. I will always retain my 50-200 as a travel zoom for it's size and weight but may get a 18-250 soon or wait to see if Pentax are making the rumoured announcement in October for the release of an 18-250