Modular digital camera systems, such as modular digital still and motion cameras are disclosed. Individual modules may be removed from the system and replaced, such as to benefit from upgraded technology, while preserving the remaining modules in the system. The modules may be disassembled and reconstructed to convert the physical form of the camera, such as between still configurations, motion configurations, ENG configurations, DSLR configurations and studio configurations. Universal lens mount modules are provided, to enable use of lens systems from a variety of commercial manufacturers.