I just bought a couple of Sigma lenses online. One was advertised as 28-80mm, but when it arrived it was 28-90mm. What gives? Does anybody know why this is? Is it something I am missing? The other lenses was advertised as 70-300mm and it was just that. I've searched a few online sites for lenses about this but only see the 28-80 ads, no 28-90. Thanks to all who respond.