i just got mine today, but it is the 4th version, which they say is not as good as the older 3 versions most especially the 3rd version. i did some quick tests a while ago and i must say that it is rather sharp. the only downside is the weight and the push-pull zoom, which makes focusing a daunting task. another thing, i worry the camera's mount while having the lens on. will weight damage the mount on the camera?
anyways, here's a photo i took a while ago. one of the quick tests i did. this one's at 210mm f/5.6