Why the old and not the newer Sigma 180mm APO macro?
Michael, let's get back to the AF question you had for enjoying the in-focus stacking feature of the D850.
I don't think Robert Otoole's tests are in any way relevant with respect to your style of photography. Since you don't shoot 1:1, his tests are utterly-irrelevant.
As mentioned, Ray Charles could see the Sigma 150 is soft as warm butter wide-open, while the CV 125 was razor sharp. For that matter, the Sigma 180 was also very sharp at f/2.8.
As better source material, I found multiple lens reviews (
from the same testing outfit: LensTip) on ALL Sigma macro lenses, that prove-out the obvious errors/omissions in Otoole's testing:
*
All of these links go straight to the resolution charts *
These tests prove what can easily be seen in OToole's limited tests, namely that the Sigma 150 is a dud at the f/2.8 aperture, which is where you like to be, whereas the Sigma 180mm (f/2.8 ) is pretty darned good.
[For comparison, check out the chart for the lens we both know you like, namely the
Zeiss 135 f/2 Apo Sonnar.
In fact, wide-open, @ 2.0, the Zeiss 135 Apo Sonnar actually
blows away every single Zeiss Otus (considerably, and with much more even sharpness across the frame):
28mm,
55mm,
85mm.
(For this reason, I just pulled my own copy of the Zeiss 135 Apo Sonnar off EBay and intend on keeping it

)
By contrast, the
Nikkor 105mm f/2.8 AF is 'meh' wide-open.
Now, if you shot Canon, the
100mm f/2.8L looks to be a great candidate, wide-open, for in-body AF ... but, sadly, it's not an option for you.
That said, when all is said and done, for in-body AF (for the Nikon D850), with a desire for
exceptional wide-open resolution, the
Sigma 135mm f/2.8 Art appears to be the lens you should consider for this specific purpose.
Although it only has a 1:5 reproduction ratio, it is very similar to the Zeiss 135 Apo Sonnar (@ 1:4), and is even sharper wide-open
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Jack