I just had this lens Ai'd and, testing it out, I find it to be quite soft at full aperture. The chap who Ai'd it did note to me that the lens rattles a bit (this was so before I shipped it to him). I decided to Ai it anyway.
If I shake the lens gently, it rattles slightly, and if I hold a tissue gently against the rear element and shake it, there is no rattle.
Thus the rear element would seem to be slightly loose, and I wonder if this affects image quality.
Anyone have any idea how to tighten the rear element of this lens?
It's not a bad lens, but I was expecting a bit more...