Lensbaby Optic Kit Interchangeable with the Composer, Muse, and Control Freak SLR lenses. The kit consists of 3 optics: Single Glass, Plastic, and Pinhole / Zone plate. Each Optic creates a different creative look in camera. The Plastic Optic has a 50mm focal length and has interchangable apertures that range from f/2 to f/22. Plastic Optic creates dreamy, ethereal images that will please toy camera lovers. The Single Glass optic has a 50mm focal length and apertures that range from f/2 to f/22. Single Glass Optic is similar to vintage camera optics, and creates a more primitive image that is great for black and white, portrait, & fine art photography. The Pinhole / Zone plate Optic allows you to switch back and forth between f/177 pinhole photography and f/19 zone plate photography. Both modes create dreamy, artistic images that are equally sharp (or soft) from edge to edge.