>>2936887its fairly sharp. the autofocus slows down and starts hunting pretty badly when you have to go down to 1/60th, f1.7 on iso 200
i usually prefer to shoot in good light conditions or with tripod.. low light shooting with an em5 is kind of a pointless endeavour without a tripod, and ive only owned it for a month, so i hadnot noticed the banding until you mentioned it.. i tested it out right now, and its not noticeable until you try to push shadows more than 1 stop on iso 800, or go past that.
Its definetly not a lowlight action lens, but as i mentioned, if youre trying to shoot moving subjects in low light with a midrange m4/3 and expect great results, you're not acknowledging the limitations of ur camera.