Abstract: An optical apparatus for viewing one or more images including (i) an optical device for enhancing the one or more images and having a surface defining mechanical threads; (ii) a display device having a display for presenting information that is removably attached to the optical device, the display device including a surface defining mechanical threads for mating with the mechanical threads of the optical device; and (iii) a lock ring that is mounted to the mechanical threads of the optical device, said lock ring being positioned between the display device and the optical device, wherein the lock ring is rotatably positioned on the mechanical threads of the optical device to move toward and bear on a surface of the display device in order to either limit or prevent the display device from further rotation on the mechanical threads of the optical device.