I recently bought this lens ("like new, in the boxβ) and I like it, except that in low light it doesn't fully focus in either manual or auto mode. In the shade, I often have to push it back 200mm or less to focus. I don't know if that's a defect or is this lens only good for excellent light conditions? When I can focus, I get great photos! Update, six months later: I had to upgrade my rating to 5 stars. I liked this lens! I think it just won't/won't focus if there isn't enough light, which is most likely not an aberration. I'm an amateur but this lens amazed me and still amazes me. Couldn't be happier with it.