[eeyore]

I use a Tamron 90mm and have had good results using extension tubes (I have the jessops set £79) and also using 2x TC - If you use both together you can get nearly 3:1 but you need to use the TC against the camera body then the tubes then the lens so that it is doubling the entire effect. Be aware that you may lose your autofocus depending on what contacts your tubes have , but as most people use MF for macro anyway this isnt a big consideration. A good book to read if you want to learn more about macro set ups is "small things big" by paul harcourt davies.