The E-P3 increases autofocus speed through use of a 120 Hz refresh rate for its sensor, similar to the technology used in the recently released Panasonic Lumix DMC-GH2 and G3 cameras.

Olympus claims, based on in-house testing, that the E-P3 has the world's fastest autofocus speed of any camera as of the product announcement date.

The E-P3 now uses a capacitive touchscreen for creative camera control, and a new OLED type display[3] that is supposed to vastly improve performance in sunny conditions, and off-angle viewing.

By comparison, the more popular consumer (as opposed to professional) DSLRs such as those made by Canon, Nikon and Sony have 1.5 to 1.6 crop factor APS-C sensors, which means larger and heavier lens designs.

[6] The equivalent Canon APS-C DSLR EF-S 18–55mm f3.5–5.6 kit lens weighs 190g, and is 69mm in diameter and 80mm in length[7] While the older Four Thirds system design standard allowed the incorporation of a single lens reflex (SLR) camera design including a mirror box and pentaprism based optical viewfinder system, the MFT system design standard sought to pursue a technically different camera, and specifically slimmed down the key physical specifications which eliminated the ability to include the traditional complex optical path and the bulky mirror box needed for a SLR optical viewfinder.

Instead, MFT uses either a built-in (Panasonic) or optional (Olympus/Panasonic) compact electronic viewfinder (EVF) and/or LCD back panel displaying a Live view from the main image sensor.

The MFT system standard also specifically includes seamless switching between still photography and HD video recording as a design criterion.