A light fixture for use in low voltage outdoor lighting systems includes a lens assembly with a diffuser lens disposed on top of a lens support, a reflector hood and a mushroom-shaped reflector retaining cap removably mounted on top of the lens assembly. A socket and lamp extend through an opening in the lens support. The radial center of the hood has a flattened area that sits level on top of the cylindrical lens and has an opening through which a base portion of the retaining cap is inserted. A recess in the top of the lens has an opening at its bottom for receiving the base of the retainer cap which is attached with a fastener inserted through the top of the lens. An O-ring seals the lens to the lower surface of the hood and the lens and lens support are sealed to provide a water-resistant seal around the lamp. The lens support is attached to the top of a mounting post.