I'm using a Schneider 80mm f/5.6 Componon-S for medium format negatives up to 6x7. I have no problems with sharpness out to the corners and no light fall off at the edges once stopped down to working aperture of f/11. Schneider doesn't recommend using the lens for that format, but it does work. The 80mm Nikkor is recommended for use with up to 6x7. See if you can find one of those around. They are both very good.