Multi-function lens cover

A lens cover for, and a method of reducing the signature of, an optical imaging system presented. A support structure is provided having a first ring-shaped end, a second ring-shaped end and a mounting portion for attaching one end of the support structure to a lens. A rotatable member is disposed at the second end of the support structure. A pliable membrane tube has a first end attached to the first ring-shaped end of the support structure and a second end attached to the second ring-shaped rotatable member so that the membrane tube forms an aperture. By rotating the rotatable member to twist the membrane tube the size of said aperture may be varied.