[Brightcolours]

Yay, a lame nonsense chart from just some nonsense source. Thanks! Let me guess, you are very close to the idea that a mediocre (even in its time) 10mp APS-C DSLR, old age and silly lens makes you imagine you are on that 40% level part of the blue line and you imagine the quality of your photos and knowledge are going up and up?

[JJ_SO]

Finally I put some comparisons together. https://sojujo.smugmug.com/Testshots/10514/n-MgKPDd

To keep it simple and easy, I just made screenshots and uploaded the PNG files. I think, it easier that way.

Couple of remarks:
The Nikkor has a yellow and the Sigma a blue label (right bottom side)
Most shots were made wide open and not all with a tripod (the fountain and the dragonfly).
While the grass on the river bank was shot form tripod there was a lot of wind going on. Here I don't want to check sharpness - as both lenses deliver outstanding results - but the fringing which distracts me and is not very easy to compensate in post, not to say "impossible".

Bokeh. I could not tell the difference just by eyesight (as long as no front light is involved). In comparison, the uncorrected vignetting of the Nikkor is obvious, but for a portrait lens no big deal (in my book).

AF accuracy and speed. I hesitate to say something about, as my comparison is lacking any scientifically relevant methods, so it's just an impression. In portraits I got more in focus shots with the Nikkor, I guess - I haven't count a number. But the Nikkor was sometimes really surprisingly far off, especially if not the center point but an outer area was selected to focus on. Nothing about AF but one reason for me to hesitate with investment: Often I reached the MFD and wanted to get closer.

Conclusion? Maybe more decision time. The decision is difficult and easy at the same time. Difficult because I like to work with frontlight - and both lenses suck in a lot of photons, not all of 'em treating my sensor nicely. If you see flare, you will not be able to ignore it, it's usually a fat spot. The fringing is so much better on the Sigma that this is a reason to buy the Nikkor only if I really really need one for supercreamy bokeh and headshots, easy to manouevre and acceptable to carry.

I just wonder why Sigma can make a 135/1.8 in a similar body like Nikkor 105/1.4, but goes beserk on a 105/1.4 design. So that makes the decison easy: Bring me a Sigma in a smaller body and take my money. Not available? No prob, the 85 and 135 are doing pretty aaaaalright.

P.S. I did see coma on stars in the corner. At both lenses' results. Surprisingly well controlled on Nikkor and not as good as Sigma tries to tell us on their portrait-bucket.

[obican]

As we've talked about it in private, I'd probably pass on both mostly due to MFD. It's beyond practical and while Nikon is tolerable weightwise, Sigma becomes even less practical when you factor in the weight.

If I had to choose between the two however, I'd probably go for the Nikon. Bokeh looks very slightly better to my eyes and I find the CA tolerable especially since Sigma has it too.

Also, good job on bringing out the worst optical characteristics in your tests. I'll copy some of your methods in the future when I'm testing a new lens.

[JJ_SO]

Thanks, obi can. Interesting, how "all of a sudden I bumped into this strange behaviour" becomes a method to check a lens. The fountain spray is something useful, I think. Some fountains do have green parts of environment around, so the green part of fringing os less of an issue. But purple or magenta is not seen so often in real and drags a lot of attraction even at thumbnails. Another unscientific method: if the thumbnail shows magenta where it shouldn't, it's too much of it in the picture.

The good thing is as well: I always try to tell people "rent the lens and see if it works for you". This time it cost me two rentals and saved me 1600.- max If I had bought the Nikkor at the dealer I rented it from, they would have reduced the price - but the lens is 400,- more expensive there, so it would not even cover the price diff.