grain, I've run through a few lenses, both Pentax and third-party, and the best of the zooms was the Tamon 28-75, while the best of the primes is the current DA-35.
To this point, I haven't found a zoom that approaches it for optical quality, or another prime that better serves my purposes as a walk-around lens than the DA-35 (compared with the excellent FA 50 f/1.4, FA-43 and Sigma 70 macro that I've tried and unloaded).
I don't know if it's the
"optical paragon" as Mike Johnson termed it but it's very good indeed: sharp from a bug's butt to a mountain skyline, good for candid portraits and urban street images, light, bright and the macro is handy to have on call even if you don't concentrate on close up work. The color is true to my eye and rich (although I mostly convert to B&W, starting with good color is important), the rendering is sharp from corner to corner, and the only thing more I'd ask of it is a bit more speed . You could say it's recommended by a very satisfied customer,
Brian