hi bros, need some advice. just bought a SAL28F2.8 from a bro here. Condition is 10, no scratches and no fungus inside aperture blades opening. However, when I took test shots(diff aperture values) at marina sq starbucks and in my room(lights on), I put on pc and see - some shots werent tt sharp while others had abit ghosting effect of blur. Can ask if any probs with the lens or issit the low light situation? All shots taken without flash.