Have been using a canon 100 macro lens and love it, but have a 100L macro with IS on the way...in doing some extreme macro, would like to use my kenkko extension tubes along with closeup lenses on the front, and, sometimes, canon 14x ringlight. I am looking for the best possible closeup lenses to get, and have read that double element rather than single element will give better quality images, however it is not easy to tell which are double and which are single element. Recommendatons for closeup filters? Also, was looking at the Canon 500D and 250D closeup lenses. Since the diameter of the new lens is 67, and canon does not seem to make these in 67mm size, I was assuming that I would need to get a larger size closeup lens and an adapter, however someone at canon said, no, I can use a smaller diameter, such as 58mm, how would this not cause vignetting? also confused as to how the ringlight adapter will work, since the ringlight fit right onto my older 100macro lens with a 58mm diameter, so wouldn't this new 100L macro IS lens be larger, at 67mm, than the ringlight opening...also, would a 1.4 or 2x extender be helpful somewhere in the mix...I like to get really far into the details of tiny parts of flowers, sometimes grasshopper portraits, etc...so any suggestions will be appreciated, thanks!