@ cls

I'm glad to be here. Haha. I use this site a lot to compare lenses using the ISO 12233 chart data.

Speaking of the Tamron, as you mention the lack of IS also bothered me, due to the fact that focusing on a subject in low light with a wide aperture is quite difficult, especially when manual focusing. As for the USM, I'm not entirely concerned about USM because I'm not into wildlife photography, and I don't mind the buzz I get from lenses when they are trying to focus.

I've been thinking about the Canon 70-200 for a long time as well. It's one of those lenses that a lot of photo-journalist have, but most have the Canon 70-200mm f/2.8 IS II USM version which in my case is way out of my budget. The main reason why I need a zoom is because I am pursing a minor in photo-journalism, so I need a lens that can cover a long range.