This is an APO version, still low price compared with Tamron and Pentax 70-300mm, sharp at 200mm, even at 300mm it is good. I used it to take many shots and like it. It even comes with a case. There's one problem with its rotated front glass, so may be trouble for CPL filter.
low price; sharp at 200mm; even at 300mm it is good
have not found so far