Anyone have both of these and can give a comparison? IQ, build, etc. I have the 28-135 and have thought of replacing it with the 50-150. I don't care to hear about getting a 70-200 or 24-105 or anything else. Just curious if anyone has had both of these and what their thoughts are. I know ones 3.5-5.6 IS and the other is 2.8 non IS.




