Fujifilm GF 250mm f/4 R LM OIS WR Aperture Series: Last Light on High Peaks (Fujifilm GFX-50R)
See my Fujifilm medium format wishlist.
This aperture series looks at across-the-frame sharpness from from f/4 through f/8 and finds a troubling issue.
Fujifilm GF 250mm f/4 R LM OIS WR Aperture Series: Last Light on High Peaks (Fujifilm GFX-50R)
Includes up to full camera resolution from f/4 through f/8.

GFX 50R + Fujifilm GF 250mm f/4 R LM OIS WR @ 204.6mm equiv (250mm)
[low-res image for bot]