Summary: I can understand why this lens only receives three stars.... At about $450.00 I expected much, much more clarity...The base Sony Lens that came with the camera is comparable!! Would not recommend this product to anyone...
Summary: I finally had an opportunity to try the lens on a Pentax K-30. I read the reviews on the pentax forums and it came out ahead of the sigma and pentax offerings in regards to sharpness. It is indeed a very sharp lens, but I do notice at times the lens will miss focus. Since I always half-way hold down the shutter to gain focus, when it misses the focus I just half-way hold down the shutter again and typically by the 2nd or 3rd attempt it gains solid focus.
Excerpt: They say: don't get your hopes up too high, and they are quite right on that. I had really high hopes for this lens, but the initial impressions are less than stellar. K-x is the current body for the lens. Let's start with the bad: 1) constant underexposure by about 1EV. 2) "purple/yellow fringing" is quite pronounced 3) slightly lifeless color rendition at times. "plasticky" probably would be a good word. Will try it on a different body, maybe they'll get along better.
Excerpt: So far, the lens is okay. I haven't seen the "wow" that most people have written about. I have a big shoot coming up. I hope it does a great job. It also turns the opposite direction for zooming. That is kind of tricky when you're used to the other way.
Summary: My experience with this is on a Canon 50D. I really waffled on returning this lens. Shooting in good light results in really sharp, really vibrant photos. Unfortunately shooting indoors in low light results in a very low rate of "great shots" when it comes to focus. This lens seems to have a much harder time focusing indoors than my widest Canon lens (28-135mm f3.5-5.6). Combined with the lack of IS, and it makes for a mediocre indoor lens when shooting without a flash.
Excerpt: There was an issue on the focus of this lens. The front focussing is a problem, and I switched it for another one of the same lens which was a bit better, but not as perfect as I was hoping for. It works great in manual and with adjustment, but that takes more time than I wanted.
Pros: Durable, Easily Interchangeable, Strong Construction
Cons: Front focus problem, Heavy, Quality Control Problem