Sigma SL 28mm f/1.4 DG HSM Art Aperture Series, Leica SL2 vs Panasonic S1R Sharpness: Desert Sagebrush
Even though both the Panasonic S1R and the Leica SL2 are L-Mount cameras, they differ in their sensor cover glass thickness, which because of ray angle interactions, damages performance for M-Mount lenses and damages performance for Leica SL lenses.
The Sigma 28mm f/1.4 DG HSM Art for L-Mount cannot be optimized for two different sensor cover glass thicknesses, so on which camera does it perform better?
Aperture Series, Leica SL2 vs Panasonic S1R Sharpness: Desert Sagebrush
Includes images up to full camera resolution from f/1.4 to f/5.6, plus crops.

Panasonic S1R + 28mm F1.4 DG HSM Art 019
ENV: east of Mono Lake, altitude 7380 ft / 2249 m, 75°F / 23°C
RAW: LACA corrected, distortion corrected, +10 Whites, +10 Clarity
[low-res image for bot]