A cover includes a base plate, an orbital disc, a plate slide and a disc slide. The cover is configured for positioning over an opening of a light-tight enclosure. The base plate includes an aperture, a bore and a slot defined therein. The base plate is configured to engage the enclosure. The orbital disc includes an aperture defined therein, a wall disposed adjacent the aperture, and a slot defined therein. The orbital disc is configured to at least partially engage the bore of the base plate. The plate slide is configured to slidingly engage the slot of the base plate. The disc slide is configured to slidingly engage the slot of the orbital disc.
