Sigma tries to make a big point that this lens has a zoomlock feature to stop zoom creep. But this lock works only at the widest end (18mm) of the zoom. Some other lenses, such as Kiron, I have used over the years had zoomlock working at any zoom position, but not this Sigma. Moreover, it is a rotary zoom, thus zoom creep would rarely be a problem. I am otherwise pleased with the lens though.