@Film-Niko You are making good points, but let me push back somewhat. First, regarding your comment on us not seeing better MF lenses in 20 years, I believe there's at least two exceptions. They are: the Fuji lenses for Hasselblad HC mount, and PhaseOne lenses. Simply because these mounts survived into the digital age.
I know, Steven. Friends of mine are using them. I haven't simply talked about them because because they are not widespread at all, a tiny niche. How many photrio members are using them? Probably extremely few. So I have just fit my comment to the audience here, to avoid writing too much.
And the second point I want to make, is that lenses like Sigma Art or Zeiss Milvus/Otus lines have achieved their exceptional performance wide open by tripling the weight & bulk of what a typical 35mm lens looks like.
The Otus line excluded (that is a very special lens line), not all Sigma Art or Milvus lenses are so big and heavy. I have used several of them, and owning some. Several are only a bit bigger than their counterparts from Canon, Nikon, Pentax. Like e.g. Sigma Art 1.4/35, the Milvus Makro-Planars, Milvus Planar 1.4/85, Milvus APO-Sonnar 2/135, Milvus Distagon 2.8/21. And sometimes there aren't even counterparts, like with the spectacular Sigma Art 2/24-35, which offers prime lens quality, and is not bigger than 3 x f2 prime lenses.
This performance requires a lot of additional glass. I have a few of these. They make sense on a 45-60MP sensor but mounting one of them onto a film camera to produce a tiny 35mm negative makes little sense, in my opinion.
I have to disagree here, and I am going in the opposite direction: With digital you are limited by the Nyquist frequency of the sensor, and you cannot fully exploit these oustanding lenses. With film you don't have that problem. And you finally can exploit the huge potential of film.
With these lenses you really see what amazing quality films like TMX, Delta 100, Acros, PanF+, HR-50, CMS 20 II, Velvia 50 and 100, Provia 100F, E100 can deliver.
When they are
not limited / crippled / degraded by old lens technology.
Probably 99% of photrio members simply don't know how shockingly good film can really be if you "take away the brakes". Because here is such a fetish about old stuff.
I like to make bigger prints, and I love to project slides on a big screen. And in both cases the new lenses are a huge progress.
They quality of slides shot with e.g. the Sigma Art 1.4/35 or the Milvus 1.4/50 or 1.4/85 in projection on a big screen is just breathtaking!!
And another important point for me: In digital I can reduce some lens flaws to a certain degree in post, like distortion.
You can't do that in your lab making silver-gelatine prints, or in slide projection.
The Sigma Art 1.4/35 has so little distortion that it is neglictable in 99% of the situation. Much better performance than the old 1.4/35 Nikkor. My Milvus lenses are free of distortion.
And all of my modern lenses have much better bokeh than the older ones, and a much better color rendition.
Therefore:
Especially as a film photographer (with generally much less possibilities of fixing or manipulating in post) I benefit from the new lenses.
The 50mm f/1.4 Milvus is just ridiculous in terms of how huge & heavy it is.
My experience is different: I find this lens well balanced on my camera bodies. And I enjoy the advantage that it even "stabilize" my hands a bit. I have been able to gain another 1/2 stop by lower possible shutter speeds for sharp results in comparison to my old, lighter 1.4/50.
It is bigger and heavier than my Mamiya 645 lenses.
Well, the Sekor 2.8/150 A is my main portrait tele for my Mamiya 645 bodies. The equivalent for 35mm is the Milvus 1.4/85. And that is more compact and much better balanced than the Sekor. The Sekor is quite front-heavy on the M645 body.
M645 + 2.8/150 is much bulkier and heavier than the Milvus 85mm on a Nikon or Canon body.
I will agree with you on the need for better coatings.
I was really positively 'shocked' by the outstanding performance of my Milvus lenses in that regard: When a 11 element lens is so much better than old 5 or 6 element lenses......I would not have expected that at all before I have seen it with my own eyes.