I recently re-aquired a 12-50 I sold. I can't remember, because I only had it for a few days before I sold it, and some 5-6 weeks have passed. However, it seems the power zoom is making a slight buzzing noise when zoomed. I compared it to a 45-175. The panasonic is silent. Is the 12-50 supposed to be also? Or does it make enough noise to be heard clearly. I ask because it is still under warranty and maybe I should send it in. As an aside, I recently received a negative rating over this lens because it supposedly is de-centered. The buyer had had it for a month and then pm'd me saying I needed to take it back ( after the buyer tried to sell it first). Initially I said no, but I would try and track down an original receipt, as the person I bought it from had taken it out of a kit bought in Dec, so it is still under warranty. The buyer then filed a paypal claim against me. I was able to obtain the ability to send it in under warranty, so, instead of fighting her, I took it back. I since have received the lens and just got done testing it against my 12/2 ,25 1.4, and a 35-100 for sharpness/de-centering. There is no de-centering. At 12 the edges are definitely softer than the oly, to be expected, but all of the way around the photo. At 25, surprisingly, it is very nearly as sharp across the frame as the panny! At 50, it actually was less sharp in the center than the 35-100 but sharper on the edges. The 35-100 was at 2.8 and the 12-50 at f8, which might explain a little. I am questioning my new 35-100 copy, though. All shots were on a tripod, with a remote shutter, and of an oil painting, which between the canvas grain, brush strokes and even plane of focus, there was plenty of detail throughout the frame. My reputation is important to me, so I'm asking anyone who might read this, to take that feedback with a "grain of salt"! Mostly, though I want to know if the noise is an issue or normal. It's audible but not terrible, where as the 45-175 is inaudible, if that helps as a comparison. I don't live close to a camera shop nor do I know anyone nearby with one, so I can't do comparisons. Any input would be helpful.