can somebody hook me up with how much of a difference these two lenses are. besides for the price and 4mm's?
Tamron SP 28-75MM F/2.8 XR Di LD Aspherical (IF)
Canon EF 24-70mm f/2.8L USM Standard Zoom Lens for Canon SLR Cameras
The main factor is image quality. You'll really notice the difference between the two side by side. If you have the money for the Canon, then go for it. Take into account that if you do get the Canon, you'll probably never replace or flip it. With the Tamron, you'd probably sell it in the future.