I'd expect that the 70-200IS is one of Canon's best lenses. That focal length range is very heavily used by many sorts of pros, and Nikon and Canon have been knocking themselves out to make a great 70-200 in order to win sales from pros. Pentax has made fewer versions of a 70-200/2.8 kind of lens, and has probably committed fewer resources to it. This is probably true of the 16-35 and the 300/2.8 as well, as these three lenses are the standard trio for many kinds of pro shooters. Canon and Nikon have made several versions since the AF era started.
OTOH, from what I understand from former Nikon users who switched to Canon, some of the wides and mid-teles are not as impressive. I think a number of these are older optical designs and focal lengths less favored by pros. Pentax might well be quite competitive outside the "pro standards" focal lengths. Certainly Pentax has made more small, good lenses than Nikon or Canon who normally opt for cheap and nasty or very good with resulting increases in size and price. And at 200mm, I wouldn't discount the A* 200/2.8, which I found to be substantially better than the legendary 180/2.8 ED Nikkor. Team it up with an A* 85/1.4 and one of the good 135s and you've got Pentax glass at least as good as the 70-200, and faster, if a bit more cumbersome and expensive. DJE
