Sharpness at 58mm

For this test, the Meyer-Optik-Goerlitz Primoplan 58mm 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 58mm

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/16. Diffraction sets in at f/22, which is decidedly soft. The edges aren't anywhere as sharp as the centre, throughout the aperture range.

Aperture	Center Crop	Edge Crop
f/1.9
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22