I have the older 30mm in m4/3rds mount and it's optically very good. When it's off the camera there's an odd rattle which makes it seem poorly built, but that goes away when on the camera so I think is something to do with the AF motor unlocking. Other than that they're very nice. I had a pair (19 and 30) for my Sony NEX which I sold a while ago and found them the same.