Useful universal lens. Sharp center even with open aperture. Borders need some F5.6-F8 across the range. Extreme borders - about 200pix aroud borders - not pleasing.
Focuses fast, good contrast, can focus closely, bokeh quite good, sealed, not big, not heavy, 7 aperture blades.. nicely matches K-5 body as multi-purpose all-in-one lens.
Hard to focus manually as there is no scale on ring.