Of all the manual zooms, I think the little 75-150mm lens is probably the most overlooked lens of the lot. It's a stellar performer in just about every category you care to grade it in. It's sharp far beyond all expectations, it's color rendition is awesome, it's build quality is.... well, it's a Pentax-M.... that pretty much says it as far as quality of build. It's easy to operate, with a good focus ring throw. What's NOT to like? No auto-focus? Aw, gee whizz! No quick-shift? Oh, Darn it! Say what? NO "A" setting? Well, I'll be hornswaggled!
But, if you can find your way past all those missing new-fangled doo-dads and whizz-bang options, then you've got yourself one hell of a nice lens! Then, if you attach it to a half-way competent photographer, it will turn out some amazing images.