Second test : simulated night. Computer screen with starfield; backlit computer keyboard; crystal vase lit by distant diffuse source. Camera: Df.
50/1.4 AIS and 50/1.8 AIS _____________________
At f/2, there is less blooming with the 50/1.4. Highlights are outlined in both cases, but they are smoother with the 50/1.4. Highlight shapes are however distinctly heptagonal with the 50/1.4, but still nearly round with the 50/1.8. Colors if the 50/1.8 AIS are more neutral; with the 50/1.4, there is a pink tint. Keyboard letters are surrounded by a slight haze with the 50/1.8.
At f/2.8, the 50/1.4 still bleeds less. Highlights of the 50/1.8 still appear bigger.
50/1.4 AIS and 50/1.2 AIS ________________________
At f/1.4, both yield the same color. The highlights, with the 50/1.2, are slightly smaller and have softer edges, compared to the 50/1.4 that shows distinct green edges behind the focus plane. In front, the 50/1.4 highlights have distinctly blue edges, which is much less the case with the 50/1.2. This result is also partly due to the 50/1.2 forward field curvature, resulting in corner highlights to be more in focus.
At f/2, the highlights of the 50/1.2 are similarly smaller, and the 9-blade diaphragme contributes to softening the edges.
At f/2.8, same observations. Overall, the 50/1.2 is slightly better, especially at 1.4.
50/1.2 AIS and 50/1.2 AI ___________________________
At f/1.2, they are astonishingly identical. I expected very similar results, not near-identity. What about stopping down, where the 9- vs. 7-blade diaphragms might make a difference?
At f/1.4, a bit surprizingly, the 7-blade diaphragm seems rounder. The 9-blade one seems slightly irregular, and less round.
At f/2, the AI version displays some more bokeh outlining (still much less than the 50/1.4), and the heptagons are apparent now. The AIS version seems to bleed a bit less in the extreme corners. Foreground blurs are slightly less mushy with the AIS. The AIS may also exhibit slightly different colors (more magenta).
At f/2.8, same observations, with the heptagons tending to appear bigger than the enneagons. So far, the 50/1.2 AIS is the best among MF Nikkors.
50/1.2 AIS and 50/1.4 SC ________________________________
I'd expect to have the best and the worst here. Not so.
At f/1.4, the backlit keys are definitely sharper with the non-AI lens, but away from the focussed keys, the blur increases much faster that with the AIS. In other words, the SC has a thinner "night DOF". This was unexpected (not completely - in fact, it is about performance degradation towards the periphery of the image). The shape of the background highlights (enneagon vs. circle) and the stronger outlining with the SC are no surprises, the latter also being quite visible by daytime.
At f/2 and f/2.8, the old SC still has a slight sharpness advantage, and the same steeper blur increase away from in-focus zones.
50/1.4 SC and Zeiss 50/2 ________________
At f/2, the lower CA and sharper center of the Zeiss are immediately visible, as is the color (leaning more to the yellow, but very balanced). The bleeding in the extreme corners is definitely less, which may partly be due to the considerable vignetting of the Zeiss.
At f/2.8, same observations. The rounded blades of the Zeiss also contribute to preserve the Zeiss advantage.
Zeiss 50/2 and 50/1.8 G ___________________________
At f/2, the Zeiss retains its considerable advantage in terms of sharpness (in the focussed zones), but the Nikkor has an astonishingly low CA, about as good as the Zeiss. The backlit keys unfortunately do not look sharp with the 50/1.8 G because of "bleeding". Here, the 50/1.4 SC is better at f/2! the oldtimer deserves an applause.
At f/2.8, the Nikkor 50/1.8 G bleeding is over, and both perform in a similar way, the remaining difference being the color cast (magenta for the Nikkor, yellow for the Zeiss).
What about the Voigtländers ? ________________________
Comparison with the Voigtländer 58/1.4 is made difficult by the FL differences. The 50/1.4 SC seems sharper in the focussed zones (bleeding, again, is the issue for the Voigtländer). Also, the Voigtländer sports slightly more decent blur circle outlines. At f/2 and f/2.8, the sharpness advantage of the SC recedes and the blur circles become similar, except that they are now heptagons with the SC, while they remain circles with the Voigtländer.
As for the 40/2: funny guy. At f/2, sharpness of the in-focus keys is as good as with the SC, but coma seems to be higher. Above all, the blur circles are outlined heptagons in the case of the SC, but atolls with a coral reef and a central island with the 40/2. Call that a "special effect". Color neutrality of the 40/2 is however excellent. At f/2.8, the 40/2 becomes much less extravagant, and blur circles are now near perfect, with a nice round shape and very discrete atolls.
Conclusion : Zeiss is pretty good; 50/1.8 G is the runner-up for color, low CA while 50/1.4 SC is the runner-up for center sharpness (with fast degradation towards the edges though), and 50/1.2 AIS for overall image quality (sharpness, bokeh) at very wide apertures.
