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. At 12mm on an P:entax K5, the 90 degree wide angle is very good, and 24mm it's a moderate wide angle and excellent. It will be very useful for building interiors and wide overall scenic views.
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.
Excerpt: Of all my lenses this is my favorite. It is just great for taking intimate shots of small groups of people at diner parties and other indoor gathereings. It is sharp and even in lowish lighting I can normally get an acceptable shot without resorting to flash (ISO has to be up a bit). The range is just perfect for this type of work and I am happy with the results of the lens. Any faults in the photos are lack of skill rather than this excellent lens.
Pros: Consistent Output, Durable, Fast / accurate auto-focus, Strong Construction
Summary: I am still learning how to use it, but this is a wonderful wide angle lens and takes fantastic pics of landscapes and structures. I shopped around quite a bit and did lots of research. I always kept coming back to the DA 12-24 for my Pentax K-x digital. The only thing that kept holding me back was the price..... much more than anything else. I have a wonderful zoom lens made for Pentax and like the feel and weight of it.
Excerpt: This lens has amazing sharpness, even when shot at f/4. I recently read an article on using a super wide angle lens for macro (yes you read that right, macro). Step it way down and this lens's depth of field and sharpness makes amazing macro shots.
Pros: Consistent Output, Fast / accurate auto-focus, Lightweight
Excerpt: I used this lens to photo landscapes and interiors. I am impressed by the quality of the pictures, minimal distortions, by very sharp images in the center, as well as on the borders, without aberrations. I am satisfied with the purchase. I think it will become my primary lens. The only disadvantage, to my mind, is its big hood. Yet, I can close my eyes on this disadvantage, as I greatly appreciate its fantastic Pentax build quality.
Pros: Consistent Output, Durable, Fast / accurate auto-focus, Sharp at all focal length, Strong Construction
Excerpt: I bought this lens for landscape and interior photography, travel photography and occasional reportage use. It is very well built, very sharp corner-to-corner even at 12 mm, resists the flare very well. I was completely satisfied. The only drawback is a quite big size (especially with the hood attached), because I use mostly compact primes, but I'm sure I'll get used to it.