I just bought a 70-200 f4L last week, and I have to admit, whoever called it a "gateway drug" leading to an addiction to L lenses was absolutely correct! It puts my 28-135 kit lens to shame as far as sharpness, color, fringing, etc. The only drawback is that it is not the IS version. I'm looking for ideas on how to get better shots at slower shutter speeds. So far, I've figured out that if I grab my right arm with my left hand, the lens will rest perfectly on my left elbow and be much less shaky. I have it mounted on a 50D with a battery grip, so the extra weight helps also. The third factor I've noticed is that 6(ish) frames per second high speed continuous is almost as good as IS, but that one good shot of ten may not be the one I wanted. So that being said, I'm polling the audience for suggestions. Please let me know if you have a technique or contraption that can help reduce the shakiness of a non-stabilized zoom.