Sharpness at 75mm

For this test, the Meyer-Optik-Goerlitz Primoplan 75mm f/1.9 lens was attached to a Sony A7R II camera, which in turn was mounted on a sturdy tripod. The self-timer was used in order to avoid any vibrations that may result from tripping the shutter. Slight tonal changes are due to slight changes in natural light during the session.

The full frame at 75mm

In the centre of the frame, sharpness is acceptable at f/2.8, improving at f/4 and reaching peak performance at f/5.6-f/11. Diffraction sets in at f/16. The edges aren't anywhere as sharp as the centre until f/8 onwards.

Aperture	Center Crop	Edge Crop
f/1.9
f/2.8
f/4
f/5.6
f/8
f/11
f/16