I was wondering if anybody here owns, or have experiences of the Nikon 18mm f/3.5 'ais' lens. It's possible I may have the opportunity to buy one in very good condition, but have come across mixed reviews with regards to sharpness. Some have rated it quite highly, yet one or two others have said it doesn't perform as well as Nikon's other 'ais' wide angles. I would be very grateful if anyone can share any opinions regarding this particular lens. Many thanks.