Hi there, Do you think the Tamron 70-300mm F4-5.6 Di VC USD lens is an upgrade to the Canon 75-300mm F4-5.6 (which i own) in terms of image quality. These are both older lenses but i have come to the conclusion that at the moment i cannot afford a more expensive lens. The Tamron i am thinking of buying is $500 new but i can get it used for $370. Too be truly honest what i really want is the Canon 70-300mm USM II but it's still out of my price range, it costs $549. I don't really know what to expect from the image quality with the Tamron, there are lots of reviews online, some say it's great and some say it's crap. Just need some advise on what you might do. Any advise is very much appreciated.