Got both of these lenses recently, the El-Nikkor is brand new and is the N version, and the Rokkor is used with a couple specks. I want to easily compare these lenses to decide which one I'll use. I was thinking of just taking portions of a 16x20 projected image (center and corners) and comparing with eye, and just comparing a regular 8x10 from each by eye. all from 35mm film. is there a better way?