The Grandagon-N with its wide image angle of up to 105° can really display its strengths in wide views in cramped conditions, e.g. in architecture or industrial photos or in panoramic views.
With the Grandagon-N, all the problems which occur in connection with large image angles have been ideally taken care of: The distortion has been reduced to a small residual value; the light fall-off towards the edges has been greatly reduced thanks to an optical trick (“pupil distortion” = the entrance pupil diameter increases when viewing at an angle); the sharpness sets standards for this class of lenses.
The eight element lenses offer not only a large maximum aperture, but also an image angle of 105°, an even more uniform illumination and distortion values of less than 1 %. The six element lens (90 mm f/6.8) is the cost-effective alternative that also impresses by its compactness which even allows the insertion into the Focus-Mount helical focuser for the use with bellowsless panoramic or shift cameras.
The use of the almost neutral gray Rodenstock center filters is recommended for critical motifs to make best use of the image circle without irritating light fall-off to the image corners.