Dear Magus: Thank you for the summary of the main lens optical charcateristics. Which lens is Lens A (or B), and which do you like more?
(i) As I said, I am very familiar with the ASPH Summilux's fingerprint and know many CVs fairly well. One of the defining characteristics of the Leica ASPH lenses is their OOF rendition. These lenses are better-corrected and therefore the OOF is 'better corrected', making for a rendition that is my preferred one but one that many don't prefer - they often characterise it as 'harsh' and tend to prefer the 'creamier' OOFs of older-generation lenses or non-ASPH lenses. Here the two lenses under discussion show precisely those characteristics (cfr. A13/B12, look at B13, B15 and compare the OOF rendition to the similarly corresponding shots in set A.
It is here where I first noticed a clear difference between these two lenses. One lens has a "harsher" [!] OOF look than the other. I am one of "those guys" who like the creamier look. Maybe it's just me.
(ii) Micro-contrast in the ASPH Summilux shows up in a very specific way. It is quite high; the CV lenses are mushier in this respect - which is my basic issue with them. Again, this matches what I saw (cfr. the wheels and backs of the cars in A17/B16 as well as the detail on that inflatable thingy in all those shots).(iii) Macro-contrast and acutance ditto - the bearded artist series shows this quite well.
This is an interesting point, Magus. The optical designs are not identical, and such fine points are results of the designs.
(iii) Handling of flare: the ASPH Summilux can be a sinner here, especially without the hood. The Nokton, however, is a greater sinner (it is, after all, a "beast" ). Again, this is what I see in the photographs (A30/B29).
I used the lens hood with each of the two lenses.
Now that we have successfully "confused" quite a few people here, what is the conclusion? Is one lens [based on my flawed field test] more appealing than the other or does each lens have its support group?
(a) Both lenses are big for a RFF camera, but the CV lens appears much larger than the Lux.
(b) The CV snapped into focus better for my eyes than the Lux.
(c) The Lux is more expensive than the CV.
(d) The CV has a max aperture of 1.2 vs. a 1.4 for the Lux.
(e) My personal taste in the external look of lenses makes me favor the Lux over the CV lens.
Points (c) and (d) would be the decisive points for my own personal decision making if one day I were to look to buy one of these two lenses. If the cost of the Lux seems "too high" [it is costly!], then it is very clear that the CV is a better option with respect to cost. If shooting wide open in very dark rooms is the main reason for getting a fast lens, then a 1.2 max aperture may prove to be a better choice than the 1.4 max aperture unless you are willing to compensate with a faster film or maybe adjust the developing process of B&W film.
If neither a 1.4 or 1.2 is really needed, there are plenty of first class 35mm lenses with max aperture of 2.0 available.
This is just my overall stream of thought at this point.
Cheers,
Raid