Originally posted by GiBi Would you say that in general Pentax-F zoom lenses are very low value for the K-1? One option tempting me was buying an affordable couple of them (the 24-50 and the 70-210 for instance), but, if they are going to kill the camera, it makes no sense.
Those F zooms won't kill the camera. They're just not as good as the newer DFA lenses, although in the f8 to f16 range they may be pretty close, at least in the center of the image. I've never used the F 24-50, but it's a well liked lens and images from it have always impressed me (beautiful color, contrast, and rendering). A few years ago I owned a copy of the F 70-210, but only shot it on APS-C, so I have no idea how it performs toward the edges on FF. In the center it's fairly sharp in the 70-100mm range, less so as you move from 100mm to 210mm.
With a lot of the older zooms, they may have sweet spots where they are almost as good as DFA lenses. For standard zooms, the sweet spot is often in the middle of the zooms range with the aperture stopped down (f8 to f16). For telephoto zooms, the sweet spot is more toward the wide end of the lens. I purchased an FA-J 75-300 for my K-1 as lightweight carry-everywhere-or-leave-in-the-car type of lens. Wide open, it's rather shockingly soft. But stop it down to f16 it's surprisingly sharp edge to edge from 90mm to 150mm.