I have a Nikon 28/2.8 AI-S coming in, and I was wondering if there is a big difference performance wise between that and the Series E 28mm? I mean like an eye opening difference in sharpness wide open. I will mostly be using it at 2.8 and hopefully for long exposure night shots. I don't have the Series E yet so I cannot compare. I am considering the Series E because it is quite small.