These are the full-frame captures but resized for web-viewing to show their flare performance. The EX really shines here over the L. Putting each lens on and off, back and forth, onto my 20D and looking through the VF, I noticed hardly any flare or specular highlights with the EX, but with the L there was quite a bit of "green" hot-spots in the VF. These images show some of what I saw. The sun is usually just out of the frame (hard conditions no doubt) and f2.8-f3.5 were used. As of note, both lenses use high quality glass elements (e.g., ELD, SLD, Aspherical), but the EX has a much simpler design with only 7 elements in 7 groups (vis-a-vis the L's 11 elements in 9 groups) which certainly had a part in the EX's solid flare performance. No hoods or UV filters were used in any of these tests.