A digital camera module is prepared as setting lens module in sleeve and enabling it to move axially in sleeve, setting conductive probe on lens module at measurement unit, arranging a strip resistance on sleeve and making position of strip resistance be corresponded to probe, enabling contact point of resistance and probe to move in following with lens module relatively in sleeve, electric-connecting a measurement component separately to one ends probe and resistance to form resistance value measurement loop of said contact point to contact end of resistance with measurement component. |