GXR is a new camera system that consists of a body and camera units. Each camera unit contains a lens (focal lengths differ between units), an image sensor of optimum type and size for the unit, and an image processing engine. By changing units, the photographer can handle a diverse range of scenes in a way that satisfies sophisticated requirements for photo expression. The slide mechanism adopted for attaching and removing camera units enables changes to be made quickly and securely. It is the lens that gives life to the photograph. In interchangeable lens camera systems up to now, the distance from the mount and the back of the lens to the sensor image plane was subject to requirements for flange back distance and back focal length. This made it difficult to achieve both compactness and high optical performance. Eliminating the lens mount, however, means that the back focal length can be freely defined for the GXR, enabling the new system to use the most optically efficient lens designs and giving it excellent potential for future expansion. This practical concept has given birth to camera units that achieve compact size without compromising image quality. Both the body and the camera units utilize a magnesium alloy exterior. Light, strong, and exhibiting superior precision-molding, heat-dissipation, and magnetic-shielding characteristics, magnesium alloy is an ideal material for digital cameras. With a non-slip "pear-skin" baked finish for both corrosion resistance and a high-class feel, the GXR exterior achieves durability, reliability, and high-class impression.