Any samples, or are they literally dupes of Fred's first copy? I haven't noticed any field curvature in mine up to this point, but I've only had a chance to shoot it once.
inksandpaper wrote:
I've looked at two copies so far and both have noticeable field curvature, bending further away off axis. Both are reasonably straight copies with regards to swing and tilt, though not perfect. The field curvature is enough to ruin corner sharpness roughly to the degree that Fred's original copy was, by my estimation. Has anyone else experienced the same? I'm not sure what I should do. Is reverse field curvature expected from this design and Fred just got super lucky?
The field curvature is bad enough that My Sigma 35 1.2 DG DN is quite a lot sharper than my CV 35/2 off-axis at F2 and F2.8, despite the former also suffering from field curvature, except it is forwards field curvature.
A matching pair from each of the two lenses which show reverse field curvature, more easily visible in the horizontal frames. Vertical frames included for anyone interested to verify focus plane tilt. The one labelled "other copy" also shows asymmetric field curvature, curving away strongly on the right edge more than on the left. One more raw included from the copy I have on hand which shows field curvature with a slightly different scene.
