Will be very curious to see Nikon 28/1.8 vs Sigma 35/1.4 results

Interesting thoughts about lens-design. I don't know if designers look to "old-school rendering". Today's lens design, much of it is defined by attributes as fast internal AF by short distance  movement of some lens groups rather than old-school lens rendering. This need of shifting lens groups do have their negative outcome to other optical characteristics that need to be corrected. Maybe that is why Zeiss lenses do have another approach by their manual lenses than e.g. Nikon, Canon and Sigma?

Lens design always is a mixed bag of characteristics, good and bad one. I do have the feeling that some characteristics don't get the attention of lens designers as I hoped they did. Many of today new Nikkor lenses do have a large amount of longitudinal chromatic aberration. Specially the f1.4 AF-S lenses are prone to this. I don't like that at all. It gives a "pollution" to clear natural colour rendering. (Also the Zeiss 35mm/1.4 is known for this). E.g. Samyang has a better result to this aspect, but maybe it is less by another lens characteristic? I think it is just a choice by the designer. E.g. the Nikkor 200mm/2.0 seems to be very good at this point. So it is not necessary at all that fast lenses do have a big amount of LoCA.

Looking to the few Sigma examples it seems this lens is corrected very well for this LoCA. In spite the bokeh could be better (the Nikkor is not the best either), it seems to me that wide open images the Sigma has the better papers for general image qualities. But let see what more reviews and examples do show.

The lens that fully surprised me in all optical aspects, for sharpness, colour rendering, contrast, micro-contrast and lack of CA and LoCA, although a quite different focal length is the new Zeiss Apo Sonnar T* 135mm f/2 that was exhibited at the last Photokina. I made several test images and was totally flabbergasted by its quality, fully wide open. (It outperformed the Macro Planar 100mm/2.0, that do have LoCA at wide openings).

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Leon Obers