Zeiss Batis 40mm f/2 CF Aperture Series: White Aspen, Late Dusk
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This series assesses corner-to-corner sharpness, field curvature and any possible focus shift, particularly in corner areas, on the 42-megapixel Sony A7R III. On a scene like this, field curvature is a primary concern because even a small amount of it will drastically reduce sharpness where the field curves out of focus, typically in the mid zones or corners.
As a close focus (“CF”) lens which Zeiss states to be excellent from 1:5 all the way to infinity (“floating lens design for consistently high image quality across the entire focus range”), the far-distance performance is a good place to start to evaluate field curvature and total performance. The MTF charts for the Zeiss Batis 40mm f/2 CF show a very consistent performance across the field, which is consistent with the stated goal.
Zeiss Batis 40mm f/2 CF Aperture Series: White Aspen, Late Dusk
Includes images up to full camera resolution from f/2 through f/8.

Sony A7R III + Zeiss Batis 40mm f/2 CF
ENV: Bishop Creek, altitude 8700 ft / 2652 m, 34°F / 1°C
RAW: LACA corrected
very blue mountain shade
[low-res image for bot]