in 1987, canon followed minolta in introducing a new lens-mount system, which was incompatible with their previous mount-system: eos, the "electro-optical system". unlike minolta's motor-in-body approach, this design located the motor within the lens. new, more compact motor designs meant that both focus and aperture could be driven electrically without motor bulges in the lens. the canon ef lens mount has no mechanical linkages; all communication between body and lens is electronic.