Excerpt: Excelent build, great focus speed and accuracy. Some PF and CA natural in such wides, but fully controllable if shooting RAW or using lens correction utilities with in camera RAW development in K-3 body. Excellent flare control.
Pros: Consistent Output, Fast / accurate auto-focus, Nice Bokeh, Rugged
Summary: a tad expensive considering it is a rebranded Tokina 12-24 which sells for about $500 for other DSLRs. This may or may not have different lens coating. I'd really like to give it 4.5 stars because I have taken so many great pictures with this lens. Would rate 5 stars if it was closer to $500.
Summary: I'm Mary's husband, and the lens was purchased for me. Some of the reviews this lens has received mention a lot of color fringing at edges of high contrasts in the scene. This individual lens exhibits very little of this optical fault.
Summary: I don't know why there isn't more love for this lens. For shooting landscapes you can't beat it - typical Pentax IQ rendering and super sharp. I am not much of a prime lens person, so this works out perfectly for landscapes for me.
Summary: Works perfectly. In my case though I find it too big and I use the 15mm from Pentax instead although this one is more versatile. Guess it's a matter of preference, so if you can live with the size I'd say this is not only more versatile than the 15mm, the pictures are also sharper on this beast.
Excellent adventure - some "width" distortion center vs edge
Deux Bits, Amazon
21 April 2013
Summary: First - I love it. Makes my trips to wonderful landscapes even more fun. Produces beautiful shots, controls flare extremely well. Works well on a K5. As other reviewers have noted - it's big, the lens hood's size makes it more unwieldy and the hood does throw a shadow with the on camera flash.