Summary: I use this lens more than any other. It is a wonderful lens that I would call all purpose. I mainly use it for portraits. It is so much nicer than the standard kit lens. This is bigger, heavier, and the circumference is a lot wider than the kit--you can tell that it is a pro lens. I bought mine with a 3 year protection plan on another site because I read that Pentax had had some problems with the lens; they were supposed to have fixed it--but I will use it so much I just...
Summary: This lens is super sharp, has a very useful focal length, focuses fast and quietly, and looks great on the camera. I used it in a night club environment on my k-r and focusing was no issue in the dark even with ISO200. Pictures have a very nice 3D effect just like my DA* 50-135 produces. If you are looking to upgrade from the kit lens look no further. This is an SDM lens ONLY no screw focus, so it may not work on the very old DSLRs.
Summary: If you had to buy only one lens to use with your Pentax camera, this one would be hard to argue with. It really hits in a lot of areas - that 1 extra mm on the wide end is nice, the macro is really decent, the sharpness is adequate in some cases and excellent in others throughout the zoom range. The zoom range is just about perfect, and the focusing is fast, accurate, and quiet. The hood is nice and works well, and the build quality is really excellent.
Summary: Really nice. Love it so far. Sold the stock lens and bought this and there is a noticeable difference in quality. This lens feels solid, is heavy and performs wonderfully. The SDM motor is smooth and quiet. The pictures are very clear all across the range. Hood is included which is nice. If you are looking for a general all purpose lens for your Pentax camera, look no further.
Summary: I had a K10 and upgraded to a K-7 a while back. The K-7 offered an extremely quiet shutter and I wanted to match it with a quiet lens. This is where the 17-70 comes in. It's extremely quiet b/c of the SDM and it complements the K-7's quiet shutter very well. I've had this lens for about 2 years and have had no problems with it. Have taken well over 15k pictures with it and am loving it more and more.
Summary: I have the DA star 16-50, but I much prefer this lens. I have had this on my K7 for a few months, and I find it a near perfect all around lens. Fast, quiet focus. Fairly fast constant f4. Great build quality. Excellent sharpness throughout zoom range with no apparent optical flaws in real life photos. A great lens that has me looking for a buyer for my 16-50.