This is what I wrote about the Noct many years ago:
The 'Noct' designation calls attention to the main application area for this super-fast lens, viz. its intended use in low-light and night photography. The front element is hand-polished to give its aspherical shape and this by necessity inflates the price of this infrequently seen optic. Improved control of coma and spherical aberration is the main reason for including the aspherical element in its optical design. This effort pays for itself by giving very sharp pictures even when the lens is used nearly wide open. In fact, performance is good even at f/1.2, really picks up at f/1.4 and simply is marvellous at f/2-f/2.8. Flare control is very good, but some ghosting can occur when extremely bright spots are included in the picture. Unusual for a normal lens, field curvature is readily apparent and focusing it closer exacerbates the situation. The prominent curvature of the field can explain why the 'Noct' scores low in tests: the corners simply are not brought into focus at wide apertures when the lens is focused on a test target. This is not the proper lens for copying or close-up photography. For shooting 3D objects however, the field curvature isn't a big issue. Beyond f/4 the image contrast also begins to decline slightly and there is a significant drop in optical quality beyond f/8. The 'Noct' is built for speed and should be used for its targeted purpose. End users also may be attracted to its special image rendition, the texture of which has an appealing 'creamy' smoothness (nice bokeh).
D2X and D200 mercilessly show that focusing accuracy is critical in order to get the maximum quality from the Noct-Nikkor. The new high-resolution D3X further underlines this fact. With such a bright lens as the Noct, manual focusing is really difficult using these cameras. This is counter-intuitive but unfortunately true.
On the other hand, if the image is properly focused, and you are aware of the strong field curvature and its possible effects on the rendition of your subject, you are rewarded with excellent sharpness and very high image contrast at settings from f/1.4 to f/4. Beyond f/4, image quality declines, after all this is a specialised design not a "normal" lens. This is further witnessed by the very good image rendition at f/1.2.
IR performance: Seems to be equally good to the visible light rendition. At f/16, and under strong contrast lighting, you might just notice the first sign of a hot spot. However, since this stopped-down setting is off-limits territory for the Noct anyway, I haven't emphasized that too much.
Who needs Imatest?