This cap covers the 5.9mm Angenieux lens that was part of an Arriflex 16mm motion picture camera operated on a number of Space Shuttle missions. Angenieux pioneered high-quality wide-angle and zoom lenses, and NASA chose them first for missions to the Moon and later for use in Earth orbit. Arriflex chose Angenieux lenses for its compact motion picture camera, a system which proved suitable for use in space until smaller digital video cameras became available.
After switching to digital video for spaceflight, NASA transferred some no-longer-needed film camera equipment to the Museum in 2004.
This object is on display in James S. McDonnell Space Hangar at the Steven F. Udvar-Hazy Center in Chantilly, VA.