Summary: A fine looking lens, and lightweight, but the goods really stop there. I did extensive testing on this lens, and I found it to be very soft from 1.8-5.6, and from 16-22, EVEN when focussing at infinity. (Worse close up, of course.) This "pancake" design (both Nikon and Pentax) is very simple and poor optically. Much better off to forget the slick looks and buy one of Pentax's 50's. I just sold my 43, and good riddance!
Pros: * Light, * Well damped focussing, * Compact, * Good flare resistance
Cons: * Very poor optics!!!!, * Awful out of focus highlights!!!, * Easy to lose the lens cap, * Expensive