My latest purchase (s/h 1D MkIII) has an anti-dust feature. It may be that it got disturbed in the post on its way to me, anyway I soon noticed a distinct dust spot in the middle of my images which was not taken out by the default turn on and turn off shakes of the filter. I had to blow it out using a Giottos Major rocket blower which is far, far more effective than any other blower I have. (In my opinion, one of the few value for money photo gadgets!)