12-17-2015, 09:47 AM
Exactly. 
I'm exaggerating - focus is usually pretty good in non-critical situations. Moving people when the camera needs ISO 12800 and wide open at 1/40 is such a situation, together with artificial colored and mixed light sources pretty much a nightmare. What I said is as well for Sigmas as for Nikkors, I don't see much of a difference in these lenses focus reliability.
Subjectively I'd say the Sigmas get higher keeper rates, but this is no solid data. If we'd live closer, I'd be happy to borrow you a couple of those f/1.4 lenses. I had only briefly direct comparison with a 24/1.4 from Nikon and from Sigma but with those wide angles is hard to tell if I missed the proper pointing at a good target or the lens missed focusing to it or the camera was confused. All I can say is both cameras brought out an equal number of good focus, with maybe a slight advantage to the Sigma as I can adjust different distances but that is only visible in close-ups and can be solved better with live view.
Side note: in regards of the 85/1.4 and the truly shallow DoF I think, I'd be better of if I had known there's a 85/1.8 around the corner being better in some aspects as the 85 is - which already is a fine glass. And was in the repair because of a AF motor failure. No repairs so far on the Sigma side, but all of those are younger than the 85.
I'm exaggerating - focus is usually pretty good in non-critical situations. Moving people when the camera needs ISO 12800 and wide open at 1/40 is such a situation, together with artificial colored and mixed light sources pretty much a nightmare. What I said is as well for Sigmas as for Nikkors, I don't see much of a difference in these lenses focus reliability.Subjectively I'd say the Sigmas get higher keeper rates, but this is no solid data. If we'd live closer, I'd be happy to borrow you a couple of those f/1.4 lenses. I had only briefly direct comparison with a 24/1.4 from Nikon and from Sigma but with those wide angles is hard to tell if I missed the proper pointing at a good target or the lens missed focusing to it or the camera was confused. All I can say is both cameras brought out an equal number of good focus, with maybe a slight advantage to the Sigma as I can adjust different distances but that is only visible in close-ups and can be solved better with live view.
Side note: in regards of the 85/1.4 and the truly shallow DoF I think, I'd be better of if I had known there's a 85/1.8 around the corner being better in some aspects as the 85 is - which already is a fine glass. And was in the repair because of a AF motor failure. No repairs so far on the Sigma side, but all of those are younger than the 85.