I am cosidering buying a new enlarging lens (this one: http://www.usedottawa.com/classified-ad/4900177). what will be the main differences I notice from the lens I have now. I have a Omega Chromega B Dichroic enlarger and the lens is the lens that came with the enlarger. it is a Rodenstock EL-Omegar F4. I have heard the nikon lens is good. bot how specifically will I notice a difference? sharpness? thanks.