Limited quantities available. 6 x 12 only.
A plano-convex lens is described by its diameter and focal length. For example, a 6"x9" lens will have a diameter of 6" and a 9" focal length. The shorter the focal length, relative to the diameter of the lens, the wider the beam of light; thus, a 6"x12" lens will emit a beam of light 3/4 the width of the 6"x9" lens. When two plano-convex lenses are used "belly-to-belly", their effective combined focal length is halved. For example, two 6"x9" lenses belly-to-belly will have an effective focal length of 4½".
