|Current digital SLR cameras with interchangeable lenses are basically based on conventional 35mm camera systems. As a result, they must be equipped with image sensors that are comparable in size to 35mm and APS film. However, because the imaging characteristics of these large CCDs are fundamentally different from those of film, a number of issues can prevent them from achieving their full performance potential. These include: (1) Although film is capable of responding to light striking the surface at a high angle of incidence, a high angle of incidence can prevent sufficient light from reaching sensor elements at the periphery of a CCD and result in reduced color definition, particularly when shooting with wide-angle lenses. (2) To achieve the resolutions required by the micron pitch of today's CCDs, the demands of optical design tend to result in the use of larger and heavier lenses.
Moreover, manufacturers of digital SLR camera systems have until now adopted the mounting systems used in their own respective 35mm film SLR cameras, making bodies and lenses produced by different manufacturers incompatible with one another.
In light of these circumstances, the new Four Thirds System standard was conceived to facilitate the design and development of digital SLR cameras and lenses that maximize the performance potential of digital imaging sensors, and provide users with product advantages such as compact size, handling ease, and enhanced functionality.