Lens for landscape-Sinar 54M/Sinar x

[galupi20]

I have a Sinar 54M ( 9 micron ) and Sinar x camera. Just need a lens for landscape. Do I need to buy a "digital" lens : Rodenstock or Schneider ? What do you recommend me ? I have a Sinaron 90mm 6.8 but I cant find samples of pictures taken with digital lenses to see the difference ?
Thanks a lot

Luis