content: As another reviewer said earlier, sometimes the QA from Sigma is hit or miss. I have had the same experience in the past. The last 2 Sigmas I have tried have been fine (14 and 150 macro) My copy of this lens for Nikon is pretty nice (sharp, decent contrast if you keep light off the front element, fast accurate focus) on digital bodies. The HSM on mine is just as quiet as any of the AF-S Nikon lenses I have. I still prefer Nikon in general, but for the limited use I have for this lens, it has worked nicely.