Coolfix is a neat lens adapter that starts off where the Nikon UR-E5 and UR-E6 left off. Basically the Coolfix is an adjustable UR-E5 and UR-E6 that screws on to the Nikon Coolpix 5000. The UR-E6 is too long for some lenses like the TC-E2+B-300 combo. If you use that combo with the UR-E6 it will vignette even at max zoom, but by using the Coolfix, you can adjusted it shorter and then it won't vignette.