If you are looking for a viewer, look no further than the fine viewers offered by Larry Heyda:

Larry offers two different viewers:
The Heydascope Ultimate — a full-package focusing viewer complete with backlight
The Heydascope Scholar — a lower priced fixed focus viewer with optional back light add-on

Both types of viewers feature massive 2″ diameter achromatic lenses with anti-reflection coating. The focal length is 75 mm, making it perfect for ortho viewing. The quality of the lenses is outstanding — the best ever seen in any medium format viewer available for sale. The standard configuration accepts the 3D World plastic mounts, however adapters for other formats can be custom-ordered.