Hi Folks.
Thanks for the replies..
I decided I am going to get this one.
Pentax | SMCP-DA* 16-50mm f/2.8 ED SDM Lens | 21650 | B&H Photo
since I have the 50-135 Big brother to it...
I was looking for a good museum type lens...so it needs to be fairly good in the dark..Today I went to one and took my Tamron 18-250 and my Tamron 20-70F/2.8 ...While the 18-250 had good range, it was really slow to focus and I had to crank up the ISO to 1600...The 28-70 F/2.8 worked real well, but not quite short enough...Just barely...