I will be receiving my 50/1.2L pretty soon and want to experiment with extreme close-ups of flowers at f/1.2. I have the option of using an extension tube or one of Canon's 2-element close-up lenses. If you have any experience using one or both of these methods, what are your impressions and the differences (if any) in the effects of each? For instance, does the bokeh change with the addition of the CU lens? (Any specific images would be appreciated.)