Thanks for the imput guys. I did look at the Sigma 150mm but its way out of my price range
(Don't want to push it
). I have just been doing a search to find as many reviews as possible on the two lens compared with the Canon 100mm, which I would have preferred to buy, mainly because I know I wouldn't be getting the dreaded error 99 which can happen with none dedicated lenses.
I may be lucky as I have just found a source for the Canon at £288
which is what I am willing to pay, so if they have one in stock it will be the Canon I get, Tamron will be my second choice as optically its the same as Canons.