I purchased this lens two months ago and I took a lots of macro shoots with it in the first few days. However, I haven't used it since few days ago when I tried to take some "normal" shoots: portraits, objects in the house and so on. The problem is, if the subject is within 2 meters from the lens, the AF seems to be working properly, but if I move a step further, the lens will just not focus. It's trying over and over again to get something into focus. Some mechanics inside are moving forward and backwards making the same sound as any lens would makes when try to focus on a wall or on a surface without details. Again, if I'm moving close to the subject the AF works ok. This happens regardless the position of the focus limiter switch. Did any of you have this problem? Is this a normal behavior because it is after all a macro lens? Thank you in advance.