02-15-2016, 12:56 PM
Like chrismiller said: Fast focus is a priority these days. And honestly, If I can maintain focus by AF as precise as I could do with a manual focusring, I wouldn't care about "well damped focus rings". Especially because these days most matte screens don't provide a focus help. And if I have to rely on that little light which is coupled to the AF module, the question remains: Why not AF from start on?
If you were referring to the Sigma 50/1.4 Art, you may notice there's a kind of a transmission between focus ring and distance scale - you need to turn the focus ring more to move the distance scale. To do is, there has to be a kind of a friction clutch, which can be programmed as manual override (by using the dock). All the latest Sigma Art and Sports lenses have this transmission, as well as all Canon and Nikon lenses with inbuilt AF-drives. Only the less costly standard zooms are misisng that detail and therefore are hard to focus precisely.
If you were referring to the Sigma 50/1.4 Art, you may notice there's a kind of a transmission between focus ring and distance scale - you need to turn the focus ring more to move the distance scale. To do is, there has to be a kind of a friction clutch, which can be programmed as manual override (by using the dock). All the latest Sigma Art and Sports lenses have this transmission, as well as all Canon and Nikon lenses with inbuilt AF-drives. Only the less costly standard zooms are misisng that detail and therefore are hard to focus precisely.