Well, the Nocton is really no Noct, but the cream it delivers is pretty rich indeed. DOF preview is considered obsolete by some, but with that lens and by that kind of settings, it is essential, as each stop will bring significant changes.
One can only dream of a version with an aspherical front element added, to get partly rid of spherical aberration and improve the "sharpness contrast" wide open, especially on close-ups. I've tested again; sharpness is quite good at 1.4m (better than any Nikkor but the Nocts), but not at 0.45m which is the minimum focussing distance.
Coma correction is less important, as it is possible nowadays to do night shots at f/2.8, a setting at which the coma already vanishes with that lens.
