Excerpt: i bought this lens to supplement my 18-55 and 55-300 which i have used very actively on my k-x (i have taken over 50,000 pictures with the camera). i also have the M 50mm 1.7, but i thought it was time to get something with AF. I wanted it mainly for pictures (portraits) of my kids, and also for product shots which i do from time to time. anyway, lens came, but very quickly i realised that it wasn't focusing perfectly.
Pros: Durable, Lightweight, Very Sharp When Focused
Excerpt: I bought this for both low light situations and for amature portrates of my grandkids and family. I've only got to mess around with it for one day for the later but loved the results. I was looking at it's newer brother and one by another company but what swayed me was the difference in cost.
Pros: Fast / accurate auto-focus, Lightweight, Nice Bokeh
Excerpt: I recently bought this lens to go with my new Pentax K-5. Coming from the Olympus system I was spoiled by the quality of my Oly 50mm. This lens does not dissapoint. Very fast autofocus, sharp, sharp images at f/4 onward but even decent at f/1.4 with very nice bokeh. The only negative (the reason for 4.5 instead of 5 stars) is the tendency for CA appearing around edges of sharply contrasting objects.
Excerpt: This is a small and cheap lens, but the results are really good if stopped down a bit.Personally I do not use this lens much as my primary interest is landscapes, but when I need a fast lens this one does the job nicely.