So just how important is that extra half step aperature in the 1.4? Enough to warrant paying an additional $200 for it? ($140 for the 1.8 vs $340 for the 1.4). I like to do a lot of theater shots, and the 17-55mm 2.8 doesn't cut it because there's just a *tad* to much movement for it. So I was thinking of getting the 50mm 1.8, since it's so much cheaper then the 1.4 - but will I regret it? If it all works out well, I wanted to get the 85mm 1.8 as well (or the 105 or 135 f/2). I just don't want to pickup a lens, then learn I should have actually gotten the other one, ya know? So what I'm looking for is a lens that will work well for theater/dance/band shooting.