I mean to say that double gauss f/1.4 or faster lenses have image quality that is so incredibly bad that it's off the scale.
Compared to 85mm or 35mm primes @ f/1.4 double gauss normal lenses have:
10 times less spacial resolution
5 times more chromatic aberration
4 times more purple fringing
4 times as much hazing
- As of 2012, the 50/1.2L tested better for resolution than any 50mm from Nikon, Zeiss or Sigma on LensRentals' shootout. That's a success.
- The 50/1.2L stopped down delivers a wonderful look that is not accounted for in those tests but that is known to photographers. The advantage of the lens is not the slight extra bit of light going from f/1.4 to f/1.2 — this is less important than ever in the digital era. And it's not the bokeh at f/1.2 — that's not a useful aperture for a lot of what a 50mm is used for. Instead, the advantage is the overall look, especially for portraits, and especially stopped down 1, 2 or 3 stops. That look is why some photographers describe it as their favorite lens. In that regard too, it's a success.
Even though you say it's a fact that 50mm lenses are "horrible", it's also fact that many photographers buy, use, enjoy and often prefer 50mm lenses. That says the photograph is what matters, not the metrics.
Even though a lens may be "just right" for some photographers, it won't & can't please everyone. A manufacturer can't make a lens that pleases everyone, or the variety of lenses that would be needed to please everyone. So whatever they make, someone will be unhappy that their personal goals for a new lens weren't met.
It appears that Nikon designed their new 58/1.4 with similar goals — it offers a very nice look, similar to the 50/1.2L based on what I've seen online. It's not surprising that Ming Thein recently wrote about the Nikon 58/1.4: "No intention of buying one since the demos I tried in Japan a couple of weeks ago were pretty soft and ‘glowy’ at f1.4 ..." It's not his kind of lens — so he bought the Otus instead.
With the 50/1.2L Canon delivered a lens that some photographers very much wanted and that measured very well in the 50mm ecosystem of its time. It doesn't please everyone, but it pleases some photographers very much. The fact that the Otus raises the bar is great, but not so relevant for the many photographers who are simply not interested in a $4k manual focus non-weather-sealed lens, even one as good as that.
Now we eagerly wait to see what Sigma brings to the table ...
You do have a meaningful point here, basically:
Canon 50mm f/1.2 @ f/1.2
Center Resolution: 4/10
Average Resolution: 0/10
Lack of Chromatic Aberration: 3/10
Lack of Purple Fringing: 3/10
Lack of Glowiness/Hazing: 2/10
Bokeh Transition Quality: 8/10
Lack of Bokeh Artifacts: 10/10
Contrast & Color: 10/10
Lack of Onion Bokeh: 8/10
Lack of Ugly Distortion: 8/10
The Canon f/1.2 L is one of the worst lenses in a few categories, and one of the best in others. Personally I like a well balanced lens.
I actually switched from using a Canon 24-70mm f/2.8 L II, to a Tamron 24-70mm f/2.8 VC because of this idea of balance because it has much better bokeh transitions, lacks bokeh artifacts, and has much better color and contrast than the Canon II, which is 3 times more expensive. Which to most people would be a hugely sacrilegious switch, considering the advantages in resolution and the fact that the Canon is an APO lens, which is mind blowing. But after using both the Canon 24-70mm 2.8 I, and II, and the Tamron 24-70mm 2.8 vc, I stuck with the Tamron. The Canon 24-70mm II just has a look that is way too clinical, it makes things look ugly and lacks color and contrast, and the bokeh of the Canon 24-70mm 2.8 I just looks busy. I also tried the Nikon 24-70mm 2.8G and it was actually between the Tamron and the Canon I 24-70mm in almost every way. The Nikon had some business in the background but was a little better controlled than the Canon.
Simply put the Tamron 24-70mm VC takes the best all around photos out of any of the Canon or Nikon compatible 24-70mm f/2.8 lenses (You can also adapt Nikon lenses to Canon and manual focus). Go figure, though I still keep a spare in case I run into onion bokeh issues, which is the lenses only major flaw.
I also don't like the Sigma 35mm f/1.4 because it takes too much away from other categories to achieve it's resolution. After owning the Sigma 35mm f/1.4 (the best one I found out of several copies) I sold it and went back to the Canon 35mm f/1.4, because it has much less purple fringing, lacks that weird mustache distortion, and has slightly nicer bokeh.
I used to be very obsessed with resolution, but experience has taught me that a well balanced lens takes better photos.
The Canon 50mm f/1.2 is not a well balanced lens though. At resolutions above 1024 pixels on the short side, it really shows a lack of detail, and even at resolutions below that you have to basically walk on eggshells to get it to create a sharp image wide open. There is no room for error. It also has a painfully high level of purple fringing.
At f/1.4 I like the Canon 1.2 over the 1.4 though because the 1.4 has very busy bokeh which is very noticeable at that aperture, even though the 1.4 has more resolution at that aperture. However I think that the Sigma 1.4 is better than either Canon at 1.4. It basically combines the strengths of both Canon lenses into one, and you can't beat that. The Nikon 58mm is basically a lot like the Sigma 1.4 wide open, except the Nikon is super sharp. It's a shame then that the other main difference is that it has so much purple fringing.
In conclusion, excluding the Otus due to price:
Canon 1.4 @ f/2.0 = best
Sigma 1.4 @ f/1.4 = best
Nikon 58mm 1.4 @ f/1.4 = too much purple fringing
Canon 1.2 @ f/1.4 (or f/1.2) = Capable of great images in the right hands but only up to web sized wide open, due to extreme softness.
Also @ f/1.4 Zeiss 50mm Sumi = Sigma 50mm = Nikon 50mm G f/1.4 (for the most part they deliver basically the same images)
I wouldn't shoot with any 50mm other than the Otus wide open though as the image quality of the double gauss design wide open is just really unacceptable.
If Sigma is releasing a new 50mm though that means that they have probably made huge improvements in image quality. Lets just hope there are no downsides.