I had the Tamron until I upgraded from it to a Sony 70-300 G series SSM lens and given the price difference you would expect a difference and there is. However, if you are on a budget you cannot go wrong with the Tamron. I spent a whole year with it and never found it wanting, I was lucky to have the £700 for the Sony. I still have the Tamron and it is not actively used by my partner.