I have bought almost all of my lenses used. I have never had any type of malfunction with any of them, and I use them very hard. I would not hesitate to buy a used lens. In fact, if a new lens was $2,000 and the same lens used was $1950, guess which one I'd buy . . . that's right - I'd save the $50 an buy the used one. As far as I am concerned, there is no benefit to buying new.