Sigma 24/1.4 wide open. No corrections in PP, so you get the full CA, distortion, vignetting, etc. Pardon the shot, I got many better portraits of Madame ; this one should at least have been cropped on the upper part, but you should see the bokeh and highlights.
For one thing, the sharpness in the center would please any dermatologist.
For the rest, CA is barely perceptible (not perceptible at all on the downsampled version). Vignetting is considerable but useful when, precisely, f/1.4 is for subject isolation. Bokeh is nice, despite some "posterizing" (left edge) that is also a characteristic of the Nikkor 50/1.4 SC, but much stronger in the latter case.
Foreground bokeh shows some cat's eyes effect on the highlights. No big issue in the present shot because they match the glittery stuff on Madame's clothes, but this could become annoying in other cases.
Now, if the Nikkor 24/1.8 happens to be even better, I can only say : get one and enjoy ! these are incredible times. I tested a rather good copy of the Nikkor 24/2 AIS at a shop, recently. But these ones belong to another class.
