01-26-2014, 01:05 PM
Quote:The focus scale on mine was way out, and I have corrected it. To me, the reduced quality at f/3.5 isn't misfocus, as you can play about with magnified live view as much as you like. Feels like a cheap fast prime wide open in that case. Probably has a wide point spread function.
Yes, f3.5 will not be as sharp. But the point was that some people that report unsharpness may be mislead by the focus scale being off, and we know it happens with this lens. The whole axial movement of the lens from minimal focus to infinity is like 0.5 millimeters. Yet, even being off by 0.1 millimeter makes quite a big difference. I think in this range, even slight variations in the mount distance can have an effect. I don't recall what the engineering specs (+/-) are for the Canon mount , and for the lens mount.