Originally posted by 123jippo My Sigma 30mm copy colors are good enough for me. Its little soft from near corners with big apetures but thats ok and understandable. But AF is not turstable at all and it makes pics keeper rate really very low but when focus is ok pics are nice. I have been using my sigma 30mm with K100D and K5 bodies and bo0th have same problem especially in low light. Maybe ur copy of this lens is better...
Here's a landscape shot from the Sigma 30mm at F/2, in camera HDR, Pentax K-x. I found the lens very usable when stopped down to F/1.8 or F/2.0. If you need to use it wide open, there's usually there's not enough light to auto focus, and the corners are pretty soft wide open.
Here's a hand held shot at 30mm F/2, ISO1600, 1/15th of a second. The bokeh is ok, except for in the edges where you get the triangular bokeh effect, with point light sources (xmas lights).