Indeed I got both lenses and have used both a lot, but never doing full A/B comparisons. To me, the use cases are different, that's why.
As a matter of fact, I got two 50/1.2 : one AIS with a slightly defect diaphragm (does not open fully - say, f/1.25), and one AI. Performance is nearly identical (and remarkable); there might be a slight difference in the coatings, and a bit less vignetting with the AI version (the AIS leans towards "clipped corners"). According to Bjørn, the different size of the rear element might be an explanation.
Now, comparing with the Voigtländer 58/1.4 :
- I fundamentally disagree with the findings of a famous tester saying it is a better lens than the Noct Nikkor for night shots. The Voigt displays bad coma and lots of "bleeding" wide open, such aberrations remaining visible (but acceptable) by f/2. So no, the Nokton should be used for daytime, or above f/2.0 at least at night (no problem with a Df though). But at f/2.8, nearly all 50mm lenses are decent, even at night.
- the 50/1.2 may be a low light lens, but not a night lens, reasons same as above (coma, bleeding).
- the 50/1.2 and 58/1.4 are similar in character : dreamy wide open, very sharp once stopped down.
- Wide open, the 58/1.4 is definitely softer (the 50/1.2 wraps a pretty sharp image in a haze, while the 58/1.4 is homogeneously mellow). This is especially true with close-up shots: on paper, the 58/1.4 focusses closer, but performance drops considerably. Its design has not been otimized for close-ups; the helicoid gets beyond the reasonable limit, that's all. However the blur is "artistically" (very) pleasing.
- On stopping down, both lenses get very sharp, but the Voigtländer is better corrected (CA, distortion), and more flare-resistant.
- I did not compare bokeh, but both are good in that respect.
- The Nikkor is probably the better lens, but costs more (factor 2.5). In fact, the Voigtländer, while hard to find, is usually sold much cheaper, so just get it if you can. On the other hand, from all my MF Nikkors, the 50/1.2 is the one with the most pronounced "3D effect" around f:5.6-f:8 (some reviewers tend to attribute that elusive quality to the 50/1.4 AIS I also own).
- Handling :the Nikkor is very good, but the Voigtländer is even better - a *lovely* lens, with precise and smooth focussing. My 50/1.2 (esp. AI) is a bit stiff in comparison.
So the praise earned by the Voigtländer might be, in part, irrational (i.e. linked with the look and feel of the tool, rather than of its images), but to the owner it may be significant.
- Last but not least - the FL is different. 50mm is a better allrounder, 58mm is much better for portraits. To me at least the difference is significant.
Herebelow, a comparison of all 50mm at hand, from last year (the Voigtländers 58 and 40/2 being mentioned "en passant", because it is *really* difficult to properly compare lenses with different FLs) :
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Test scene : a kitchen corner at about 1.0m. The preferences expressed below therefore apply to 3D subjects, not to flat subjects. Backlighting and flare resistance were not tested. And night shots are another completely different subject; see test setup #2 below.
The camera was a D800, so it may exacerbate differences that would remain unnoticed on a D700 or Df.
All tests were done using LV focus, so focus shift did not arise. From manual focus adjustments performed, I'd say that the 50/1.2 is most prone to focus shift. I also suspect (from relatively frequent misses in practice) that the 50/1.4 SC shifts focus to the rear. On the other hand, it delivers enough keepers; MF uncertainty (moving subject, moving operator) exceeds the shift values, so the statistics are not dramatically affected.
With all other lenses, focus shift seems to be a non-issue (i have heard different opinions about the 50/1.2 though).
Comparisons were made in Lightroom, using the X/Y comparison function.
50/1.4 SC vs. all others ______________________
The 50/1.4 is an "it" lens. It is least sharp and less contrasty wide open, exhibits more nervous bokeh, and somewhat more distortion (only the 50/1.2 beats it) and vignetting. Its colors are cooler. From 2.8, it is excellent in the center, as all others would be too, at least when tested on the Df (16 Mp sensor). I cannot mount this non-AI lens on the D800, so comparisons end there.
On the other hand, in real photography life, this lens does not disappoint. Even the wide apertures are usable for all sorts of "artistic" effects, and the center is very sharp already at f/2.0.
The 50/1.4 SC exhibits significant bleeding (on night shots) and a crazy bokeh on bright backgrounds, reminding some "fauvist" paintings.
My copy is a late, multicoated version (manufactured 1974-1975); if you can find one for a low price, do not hesitate, the reward will easily exceed it. The handling is also excellent... on Df (reminder: non-AI!).
50/1.2 AI vs. 50/1.2 AIS ______________________
At all apertures from 1.2 to 4.0, they are virtually identical. Differences may be due to slightly changing lighting conditions, and sample variation (centering). It seems that the AIS colors are slightly warmer, and the contrast may be very, very slightly higher. This hints at modified coatings. There are no obvious differences in vignetting at the chosen focussing distance.
50/1.4 AIS vs. 50/1.2 AIS ___________________________
At 1.4, the 1.4 is distinctly sharper over most of the field. Accordingly, the bokeh is more nervous (more outlining, with green outlines in the background owing to LoCA). The 1.4 also exhibits lesser purple fringes on shiny cutlery edges for instance. The 1.4 vignettes more, as one would expect. It is also likely that the 1.2 has some forward field curvature (towards the camera), at least if compared with the 1.4. The 1.2 is slightly warmer.
At 2.0, both are similar, but for the vignetting, still higher with the 1.4. The 1.2 exhibits distinctly more lateral CA that can of course be corrected. The field curvature difference is still apparent.
At 2.8, vignetting levels out, and bokeh is roughly the same. The 1.4 is still a tad sharper. No changes in field curvature differential.
At 4.0, the only remaining, significant difference is the considerable lateral CA of the 50/1.2. Once CA is corrected, I still have the impression that the 50/1.4 is slightly sharper in the center, and possibly elsewhere too.
50/1.4 AIS vs. 50/1.8 AIS ___________________________
My 50/1.8 is a recent (short nose, pancake) version, plasticky and with minimum focussing distance greater than 0.6m, so not the best choice, but for the chosen scene, it does not matter. I also got a 50/1.8 AI, which is better in both respects but with damaged coating, so it is being used as a paperweight.
At f/2.0, colors and vignetting seem about the same. Center sharpness for the 50/1.4 is better; the 50/1.8 is still marred by some haze. Bokeh is similar in shape and tint (such as green outlining in the background), but the 50/1.8 has more outlining. The 50/1.8 seems to exhibit slightly less LoCA in the foreground; the 50/1.4 has more purple fringing, where the 50/1.8 rather produces blue fringes on shiny parts.
At f/2.8, the overall pictures are hard to tell apart. The 50/1.4 still has the very slightly better center sharpness. The actual FL of the 50/1.8 is also slightly longer. The bokeh is now about the same (both lenses by the way have a 7 straight blade diaphragm, so you won't expect more differences on stopping down).
At f/4.0, differences narrow further down. I still see slightly better center sharpness with the f/1.4 lens.
50/1.4 AIS vs. 50/1.8 G ________________________________
At f/2.0, and to my surprize, both lenses are very close. Center sharpness of the 50/1.4 might be slightly better, but the 50/1.8 G delivers better edges and a more homogeneous field. This remains to be checked with a flat subject. Bokeh is similar, with maybe a tad more green LoCA with the 50/1.8 G. On the other hand, the cutlery is "cleaner" with the 50/1.8 G, so globally it is a tie.
At f/2.8, differences vanish. Strangely, the 50/1.8 G seems to have a lesser DOF.
At f/4.0, the 50/1.8 G has more contrast and takes over, if perceived sharpness is the criterion.
50/1.8 G and Zeiss 50/2 ZF2 __________________________________
At f/2.0, the first thing you notice is the relatively warmer Zeiss rendering. In my opinion, the 50/1.8 G is more neutral, so let's call the Zeiss "yellowish". Center sharpness of the Zeiss beats everybody else, including that of the 50/1.4 AIS (that is not very far behind). I'd call that a one-stop difference...
The Zeiss has slightly less CA. Bokeh is about the same. However, its sharpness field is not flat; the corners bend to the rear (away from the camera). This may be interpreted as "more nervous" bokeh, where in reality background details in the corners are more in focus, in other words less blurred...
At f/2.8, center sharpness of the Nikkor catches up, so both are now comparable. What remains is the field curvature and the color temperature.
At f/4.0, field curvature and the very slight remaining CA of the Nikkor is all what tells them apart. The closest corner is now brought in focus by the Zeiss, while the Nikkor insists that no, that corner is not in the same plane. And once again, I dare say that the Nikkor may be sharper in the center...
Bottom line ? _____________________________________________________
All lenses are very usable. The 50/1.4 AIS has the best performance amongst MF Nikkors. Wide open, the 50/1.8G, while very good, may not be the best, but wait until I perform night tests... or until I shoot against the light. The Zeiss is in a category of its own, given its extreme shapness wide open (and in the center) and quasi-APO, but beware of field curvature. And, as you may know, the ZF2 version which I own is, alas, nuts against backlight as soon as you stop down...
Second test : simulated night. Computer screen with starfield; backlit computer keyboard; crystal vase feebly lit by a 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 of the 50/1.8 AIS are more neutral; with the 50/1.4, I observe a pink cast. 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 still appear biggerwith the 50/1.8.
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 fares 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. 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 towards the yellow, but still 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 exhibits 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.
