If The Tamron 28-75 is as good as or even better than the Canon 24- 70, why should we buy the heavy and ridiculously expensive Canon 24- 70? I think either Tamron can raise their price up to $700 or Canon should drop their price down to $700. Optically, How can Tamron make a 510g lens that is as good as a 950g lens? I would like to hear from you so I will sell my Canon 24-70 and buy back the Tamron 28-75 that I have sold it last month. Thank you.