This is a big honkin' Pentacon-6 medium format lens (150mm f/2.8) adapted to the K-mount. The front element is ridiculously huge and has no hood, which paired with the lack of multicoating and the lack of a hood meant pretty low contrast. But much of that can be saved in PP. The lens is an interesting beast. It's somewhat soft wide open, but probably in a good portrait-y way. Like most, it sharpens up as you stop down.