A digital camera module includes an image capture device, a lens unit, a housing for receiving the lens unit and positioning the lens unit with respect to the image capture device, and a focus mechanism disposed on the outside of the housing and operative to move the lens unit along an axis when the lens unit is rotated about the axis. In one embodiment, the focus mechanism includes a ramp formed on the housing and a complementary ramp formed on the lens unit. In another embodiment, the focus mechanism includes a thread set formed on the outside of the housing for engaging a complementary thread set on a sleeve of the lens unit. In still another embodiment, the focus mechanism includes an inclined groove and a groove follower. The external adjustment mechanism prevents the image capture device from being contaminated by particulates generated during focusing.