11-28-2014, 02:42 AM
Been playing with the 16-35 and corresponding a little with Lloyd Chambers about it.
He has detected interesting forward focus shift with it using firmware 1.01 on the a7r
He says (preliminarily) it seems to go away using the firmware 1.1 (which came out just before the lens)
DXO are showing the periphery getting slightly worse at f5.6 from f4, which on a full frame lens suggest focus shift. I wonder if they used firmware 1.01?
I'm on 1.1, and haven't found any yet (but have not exhaustively looked)
Hypothesis: either there is a bug in 1.01, or more plausibly, there is native focus shift in the lens but it's corrected for in the 1.1 firmware.
If so that's cunning: if you can make a lens cheaper or sharper by allowing a little focus shift, and then compensate for that by moving the focus (assuming not too much curvature of field) in firmware, that's the kind of lossless goodness I'm all in favour of.
Anyhow, if Klaus tests this one it'd be good to know which FW he uses!
He has detected interesting forward focus shift with it using firmware 1.01 on the a7r
He says (preliminarily) it seems to go away using the firmware 1.1 (which came out just before the lens)
DXO are showing the periphery getting slightly worse at f5.6 from f4, which on a full frame lens suggest focus shift. I wonder if they used firmware 1.01?
I'm on 1.1, and haven't found any yet (but have not exhaustively looked)
Hypothesis: either there is a bug in 1.01, or more plausibly, there is native focus shift in the lens but it's corrected for in the 1.1 firmware.
If so that's cunning: if you can make a lens cheaper or sharper by allowing a little focus shift, and then compensate for that by moving the focus (assuming not too much curvature of field) in firmware, that's the kind of lossless goodness I'm all in favour of.
Anyhow, if Klaus tests this one it'd be good to know which FW he uses!