Lens for 20x20 or 24x24

Bertil, you are much too trusting and and aren't thoughtful enough. Apo-Nikkors are narrow angle process lenses. Shorter ones (150 mm - 240 mm) just cover their focal lengths at infinity. Longer ones have less coverage.

The coverage figures you posted are for 1:1, are twice the lenses' coverage at infinity. See this: http://www.galerie-photo.com/apo-process-nikkors-en.html .