An electronic camera module incorporates a sensor unit (20) having a semiconductor chip (22) such as a CCD imager and a cover (34) overlying the front surface of the chip. An optical unit (50) includes one or more optical elements such as lenses (58). The optical unit has engagement features (64) which abut alignment features on the sensor unit as, for example, portions (44) of the cover outer surface (38), so as to maintain a precise relationship between the optical unit and sensor unit.