A surveillance camera has a housing, a photographic lens installed in the housing, and an adjustment mechanism connected to the photographic lens. The photographic lens has a first adjustable lens for adjusting distance, and a second adjustable lens for adjusting focal length. A distance adjustment ring is coupled to the first adjustable lens, and a focal length adjustment ring is coupled to the second adjustable lens. The adjustment mechanism has a support, a first adjustment screw, and a second adjustment screw. A first adjustment ring installed on the distance adjustment ring of the photographic lens has teeth corresponding to threading of the first adjustment screw, and a second adjustment ring installed on the focal length adjustment ring of the photographic lens has teeth corresponding to threading of the second adjustment screw.