Also, I figured I should mention something about glass type.
There's a lot of hype about ED glass, and to be honest, it's mostly true. ED stands for extra-low dispersion, which helps with image clarity and brightness. ED glass, regardless of whose name and logo is on the optic, is going to produce a brighter, clearer image 99.9% of the time - the other .1% is when it's pitch black and doesn't matter. If you can afford ED glass, you should get it.