Ok, I checked the archives and Carl Weese said the 355 Schneider G Claron will work, other sources on that same thread said a Nikon 450 would cover it. How about the Rodenstock Apo ronar, Armin was asking about? has anybody used this lens with a 12x20? I am looking to upgrade my lens and would like the opinion of the forum. Thanks all! I know the Apo Ronar has an image circle diameter of 323 at f/22 but does the image circle will be big enough at f/45? by my calculations the diagonal of a 12 x20 is 496 mm, so I need a whole lot more than the lens seems to be able to provide.