well, it's a good way to figure out which lenses you can get rid of :P
Getting rid of lenses? What are you talking about. Lenses are supposed to be bought, not sold

I bought the Tamron 17-50 yesterday, and put it to good use during the evening. Either I've got a stellar copy, or it's just one of the greatest lenses. And I don't need no stinkin' program to tell me what aperture it will be used at. I've already glued it to f/2.8
