01-25-2018, 08:14 AM
"How do YOU explain the lens' reliability on a D500 and unreliability at D750?"
Generally up till now I have very few differences in lens AFFTs between the two cameras.
Sigma has to reverse engineer their AF algorithms as best they can, that IMHO plays a large role......for instance the lens information that identifies the lens itself is incomplete.....many memorized AFFT settings are confused between themselves, my K mount Sigma 105mm macro (now gone) worked fine but took on the same AFFT settings of my old Bigma..if you change the setting for one it would change the other...the two identification codes were seen by the camera as the same.
As far as I know all Nikon's lens identify themselves independantly.
​ None of the third party lenses use the full features of the later Nikon AF system ....even many of the older Nikon lenses do not either, Nikon publish a list of lenses that "do" use the full facilities available.....when I find it again I will post it.
Between the lens identification codes and the fact that Nikon will not licence their soft ware to Sigma or Tamron for that matter puts them at a disadvantage, as to how much that affects things in the end is another question!
So enter the USB dock.......it gives us ordinary folk the opportunity to make our own settings straight on to the lens....a get round for those capricious lenses which had AF quirks here and there and giving us independence from the service departments.
If you don't start out with Nikon's blessing, a manufacturer is out on his own when it comes to exactly what is needed to get the job done without hiccups........and effectively Sigma and Tamron are out on their own!
There are many subjects that thanks to internet have been explained, exposed and been thoroughly understood, right down to the last detail, the exact working of PDAF isn't one of those!
Generally up till now I have very few differences in lens AFFTs between the two cameras.
Sigma has to reverse engineer their AF algorithms as best they can, that IMHO plays a large role......for instance the lens information that identifies the lens itself is incomplete.....many memorized AFFT settings are confused between themselves, my K mount Sigma 105mm macro (now gone) worked fine but took on the same AFFT settings of my old Bigma..if you change the setting for one it would change the other...the two identification codes were seen by the camera as the same.
As far as I know all Nikon's lens identify themselves independantly.
​ None of the third party lenses use the full features of the later Nikon AF system ....even many of the older Nikon lenses do not either, Nikon publish a list of lenses that "do" use the full facilities available.....when I find it again I will post it.
Between the lens identification codes and the fact that Nikon will not licence their soft ware to Sigma or Tamron for that matter puts them at a disadvantage, as to how much that affects things in the end is another question!
So enter the USB dock.......it gives us ordinary folk the opportunity to make our own settings straight on to the lens....a get round for those capricious lenses which had AF quirks here and there and giving us independence from the service departments.
If you don't start out with Nikon's blessing, a manufacturer is out on his own when it comes to exactly what is needed to get the job done without hiccups........and effectively Sigma and Tamron are out on their own!
There are many subjects that thanks to internet have been explained, exposed and been thoroughly understood, right down to the last detail, the exact working of PDAF isn't one of those!