What we need is a good ole fashioned thread where everyone gets to justify a magic piece of Pentax equipment. So: If you had to go photograph, and you didn't know where or what or why, what lens would you take with you? You get only one.
I, personally, would take an M50mm f1.4. Fast if you need it, can be pressed into service as a "near portrait" lens, capable of good scenics, and fast for any available light opportunities. The closest zoom I have to this is an A 35-70, but it ain't nearly as easy to focus, so I'd leave it behind.
