Sharpness at 35mm

For these tests, the Olympus M.Zuiko Digital ED 12-45mm f/4 Pro lens was attached to an Olympus OM-D E-M1 Mark III mirrorless camera, which in turn was mounted on a sturdy tripod. The self-timer was used to avoid any vibrations from pressing the shutter release. Slight tonal changes are due to slight changes in natural light during the session.

The full frame at 35mm

Centre sharpness is commendably high even wide open at f/4, with peak performance achieved at f/5.6. Diffraction kicks in at f/16 and gets worse at f/22. The corners are also very sharp at f/4, with the best performance again at f/5.6.

Aperture	Centre Crop	edge Crop
f/4
f/5.6
f/8
f/11
f/16
f/22