Hi. Thanks to everyone for your comments. I purchased the Tamron plus the extension and mount adapter on eBay last night for £78 (fully boxed and instructions). Good price? Can't wait to try it.

I guess like most things in life ... I won't really know exactly what i want until I try it. I want to photograph beasties for sure, butterflies etc. Anyone else have the extension tube or 2x convertor and hardly use it? (If this is the general case, then I will just buy the lens and forget about the extension tube or the 2x convertor). Comments appreciated.

As I said, I'm new to Tamron lenses ... could you clarify this for me. Do i need the extension tube to get 1:1 macro?

I have the opportunity to purchase this lens for my Samsung GX10 which would give me a 1:2 macro facility. I am new to Tamron Adaptall lenses. There is also an extension tube that would result in 1:1 My question is though .... since the Samsung (as also the Pentax K10D) has a factor of x1.5 ... do you really need the extension tube to get you up to 1:1? Would the basic lens and the x1.5 factor not bring me up close to true 1:1 anyway? Am I missing something? Comments appreciated.