06-20-2014, 11:35 AM
I got the Sigma 50 Art not long ago. On my first test out, the AF seemed a bit hit and miss and I realised the body AFMA was set to +17! The lens shows as a 50mm on the body, and I think since I used the Zeiss 50 Makro before, it was using the value from that. Even though the Zeiss was a MF lens, I had to set the AFMA to get the focus assist to work accurately.
Since then I ran FoCal on it, and that came up with a suggested value of -4 (at body), which makes me surprised anything was in focus at the previous setting of +17. I haven't yet tried setting it using the lens dock.
The recent versions of FoCal include analysing the RGB channels separately. The Sigma showed red and green to be close to each other, but the blue channel was further away. This may be a way to look at longitudinal CA effects. I was a bit surprised at blue being the odd one out here, as on other lenses I'm fairly sure (subjectively) that the red is off compared to green+blue.
Since then I ran FoCal on it, and that came up with a suggested value of -4 (at body), which makes me surprised anything was in focus at the previous setting of +17. I haven't yet tried setting it using the lens dock.
The recent versions of FoCal include analysing the RGB channels separately. The Sigma showed red and green to be close to each other, but the blue channel was further away. This may be a way to look at longitudinal CA effects. I was a bit surprised at blue being the odd one out here, as on other lenses I'm fairly sure (subjectively) that the red is off compared to green+blue.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.