ahalpert
Major Contributor
I don't know that specific Sigma lens, but I can tell you from my research and the lenses that I do know that heavy lenses and telephoto lenses benefit from using multiple autofocus Motors to move the glass quickly and accurately. For example, my Tamron 70-180 F 2.8 uses 2 autofocus Motors and the autofocus is really fast. The Sony GM 135 and the Sony 50 GM both use 4 autofocus Motors , 2 for each focusing group to push and pull from opposite directions. The footage I reviewed from the Sigma 35 F 1.2 had really disappointing autofocus performance. The look was beautiful, but the autofocus move slowly and, more troubling you could see the motor stepping at discreet intervals through the range. I think that more and more lenses will be employing multiple motors, which has been the trend
