Remarkably, with the exception of the optical viewfinder, the E-P1 seemed to fit most of the features found on the Olympus E-620, a larger Four Thirds system DSLR, into the small, compact MFT form factor.

The E-P1 does not have a built-in optical or electronic viewfinder, but instead uses the large 3-inch (76 mm) inch color "HyperCrystal" LCD on the back of the camera.

Olympus did offer an optional accessory hotshoe mounted optical viewfinder, the VF-1, that provided for a 17 mm lens angle of view The E-P1 auto focuses using contrast-detection.

In an interview, Mr Akira Watanabe, SLR Planning Department Manager for Olympus Imaging, said that for a number of reasons Micro Four Thirds was developed to meet the demands of those who wanted a DSLR, but without the size problems that come with one.

The Panasonic G1's body is SLR-style, with the bump on the top of the camera, where the pentaprism is placed in SLR's, in the G1, it houses the electronic viewfinder.