Summary: The high definition shooting mode of the Olympus OM-D E-M5 Mark II is investigated by simulation of line-pair images. The half-photosite shift that is employed to produce 64MP images from a 16MP sensor can, in principle, double the linear resolution that is otherwise achieved by the camera without sensor shifting. However, image pixels obtained at the shifted sensor position are not independent of pixels obtained at the unshifted position: the two sets of pixels overlap completely, with a half-photosite offset. The result is that micro contrast is reduced in comparison with a true doubling of the linear photosite resolution. Given the 3.73 µm photosite pitch of the E-M5 II sensor, the resolution benefits of sensor shifting decrease rapidly at apertures smaller than about f/5.6 because any potential gain in resolution is overwhelmed by diffraction blur (coupled with non-independence of shifted and un-shifted image pixels).
Key words: Olympus OM-D E-M5 Mark II, sensor shift, resolution limits, sampling frequency, diffraction, photosite size, perfect lens, line-pairs, simulation, Airy disk, diffraction-limited resolution, sensor-limited resolution