This was just a chance to play with two new lenses. A 300 2.8 Canon L and an Tamron 70-200 2.8 that I just traded for my 70-200 F4. They both passed the test. Even in a dark room, handheld, I get passable results (frog and bats).
For anyone considering a 70-200 2.8, the Tamron is right up there with the current OEM lenses minus about $1000 off the price. It's not a tank like an L lens but I take very good care of my gear so I don't need a tank. This is my second Tamron lens and I will say with confidence that they are truly awesome pieces of glass. The Color rendition and sharpness they produce cut my post time waay back. I'm glad to find a less expensive alternative to the crazy inflated prices Canon L lenses have grown to since the Tsunami.