I've had two 50mm manual focus lenses fall into my lap, and need to decide whether to get rid of one, and which to keep. Both are in excellent condition, so that won't really matter. I know the best thing to do would be to go out and shoot a couple of hundred shots with each and make my own decision, but I don't think my skills or my eye are quite at that point yet. Also, it is kinda cold in Milwaukee for shooting a few hundred shots right now. So, between an AI Nikkor 50mm f/2 and a Series E 50mm f/1.8, which would be the better lens? I know build quality is better on the Nikkor, but if the optical formula used on the Series E is better I might put up with all the plastic. In searching for opinions, so many other lenses come into the discussion that I'm not clear where these two stand relative to one another.