thanks Rick, I know you have both. I didn't do a lot of research before I bought it. mainly is because I already have the 100mm non L and I want the better bokeh the 180mm can do, but my 180mm doesn't seem like a lot better than my 100mm in term of sharpness and color, but of course the bokeh is better, but still, I am kind of disappointed. maybe I need do more work to know this lens better. but what I really hoped was a new 200mm 4.0L IS macro anyways[]