Originally posted by Winder No lens with the STAR designation should have that much LoCA. I'll say the same for Canon and the new 50mm F/1.2 RF. No top of the line lens should show fringing that bad.
That Sony of yours, according to DxOMark, has as much chromatic aberration as the Pentax DA*55, so don't start, @Winder!
It also has massive vignetting that is obviously coped with by baked in RAW corrections - 2.5eV! - like all the other baked in corrections, including for the bands of sensor pixels that can't be used for the picture because lacking a mirror and dedicated AF module they're needed for the PD autofocus, and heavy handed RAW noise reduction that eats stars.
The Pentax does not show any more chromatic aberration than any other f1.4 high quality lens when properly measured. ePhotozine is the only review site that did and concluded: "CA (Chromatic Aberration) is very well controlled, the centre especially so. In general shooting CA does not seem to be a problem, even in demanding situations such as branches against bright sky or the shot of the Astley Green head gear."
The Russian dude showed it's *less* than the Zeiss, just have a read of his data, linked above.
DPR offered no measurements, just cherry picked photos.
If you send me your A9 and Sigma 50mm Art, I will get purple and green fringing photos out of it, and then send them back to you!
Below is the Sigma 50mm Art. Credit: Lens Review and field test: Sigma 50mm/F1.4 HSM DG ART lens ? Akshay Jamwal Photography