The present invention provides an automated luminaire with more repeatable, identical and accurate movements by normalization for motion drive system hysteresis. With some implementations, an instrument is provided with a bezel surrounding a crystal, wherein the upper surface of the bezel extends above the upper surface of the crystal. In addition, after the shoulder belts are inserted, one blocking member can compress the shoulder belts, and the other blocking member can completely seal the clearance for inserting the shoulder belts, which result in the shoulder belts being not slid out from the hook coupling.