Olympus E-M1 + 12-40mm f/2.8 PRO @ 12mm: Aperture Series with Diffraction and Quality Discussion (Boulder Logjam)
In Guide to Mirrorless the Olympus 12-40mm f/2.8 PRO zoom is evaluated on the Olympus E-M1 in an aperture series from f/2.8 through f/11 along with large crops.
Boulder Logjam in Lundy Canyon (12mm, EM1)
This example shows the effects of diffraction in 1/3 stop increments in the f/5.6 to f/11 range, with results that are well worth understanding. Distortion and its effects are also discussed and the example has been added to the Raw Converter Silent and Uncontrollable Correction for the Lens page.