The new camera gets sensor-shift image stabilization and on-sensor phase detection as part of an updated 24MP sensor. The camera's 28mm equivalent F2.8 lens has also been redesigned and a touchscreen added for the first time.
The GR III's sensor can now shift in three axes to compensate for camera shake and this shake can simulate the effect of having an anti-aliasing filter.
The redesigned 28mm equiv. F2.8 lens will have six elements in four groups, including two aspherical elements. The minimum focus distance has improved to 6cm (2.4") from 10cm (3.9"). The built-in 2-stop ND filter from the GR/GR II remains. The GR III can record 1080/60p video, up from 1080/30p on its predecessors.
Ricoh says that the new camera will also have an "improved user interface."
The RICOH GR III will be available in early 2019.