Someone was asking a few days ago about using the Canon Mr-14EX with a 180mm macro lens. I got my converter a few days ago, and finally had a chance to try it out this weekend. It works great. The converter is sort of a stepdown ring...it screws into the front of the lens, and the flash attaches to it. I found a holly bush in bloom, and was able to snap a few critters buzzing around the flowers.