I'm going to buy one of these 2 lenses in the very short future. My question is this. Is the 1.4 superior enough in speed and image quality to warrant the extra money? I have no problem spending that much on it, but not if it's only marginally better than the 1.8. I don't have a really sharp lens and would like to add a nice sharp lens for portraits to my collection. And it seems like the 1.4 is going to be the best bang for my buck.