Excerpt: This is just the lens I needed for shooting pictures in museums, where the lighting is universally horrible, and where exhibits are so close together you have to be very close to the subject. At f2.8, coupled with the higher ASA possibilities of the Pentax cameras, lighting is no longer a problem. In most cases, I can shoot without a flash, so as not to get reflections off display cases and chrome. And of course, depth of field is never a problem with wide angle lenses.
Pros: 90 Degree Fov, Fast F28, Perfect Pentax Optics
Summary: Photographers who have been around for a while and know a bit of history, know that Pentax has often delivered good quality equipment. Pentax users are a resilient bunch ever unbending to the likes of Canon and Nikon. And yes, they do have a reason for that. Pentax may not spend a lot on marketing (hence such little brand awareness amongst the younger generations), but heck I guess they're too busy spending every penny they've got actually making great products instead...
Summary: I am a Canon shooter (I shoot a 5DM3) and this 15mm Limited prime is the main reason why I am still hanging on to my Pentax cameras. Great piece of glass. When paired with my Pentax K5, it is my ultimate landscape setup. Unbelievably sharp at F8.
Summary: Although I have only used the lens once for a walkabout in town to test it, it appears to be a quality lens as already commented on...just a bit of information if anyone plans to use a protective filter...which I prefer to do...due to the fixed lens hood the first filter I tried did not work...I now have a Hoya NXT HMC UV filter mounted...which does not impede the lens hood and is threaded on the outside so the supplied lens cover will screw onto it...
Summary: I considered this and the 14mm Pentax, and went with the 15mm based on reviews of lower distortion, and also due to its compact size. I also considered a wide angle zoom, but they were pricey and suffered to various degrees on poor resistance to flare and had more issues with CA and distortion. I am very happy with the choice. I have used it primarily for landscape photography, and occasional tight shots for the forced perspective.
Summary: This is the firs wide angle lens I have, and I am very happy I bought this one. Bought this lens at a very reasonable price. The image is very very sharp even it is wide open. Could be low light use. The build quality is solid, you can feel it when you hold it. The auto focus is very fast and accurate. The only down side I can think of is the lens hood, it is huge. You usually get two different look from the people after you put the lens hood on.
Summary: Quality metal build. It's on the hefty side compared the DA 15mm. Love the short minimum focus distance. Little soft wide open but super sharp stopped down. Lovely detail with low distortion. Prone to flare, so watch the light.
Summary: Excellent piece of Pentax glass. Very good picture quality. Higher vignetting at f2.8-4, distortions are no issue, a lot bigger than DA15/4 but better handling. Beware of large 77mm filters you'll need.