The Composer Pro II with Sweet 50 Optic is a 50mm f/2.5 selective focus lens with a 12-blade adjustable aperture. This lens enables you to illuminate the essential details at 50mm, creating wonder and feeling in your photos. Place the sweet spot of focus anywhere within the frame by tilting the lens to spotlight specifics in portraits and enhance everyday scenes. Aperture ranges from f/2.5 through f/22. Along with controlling depth of field, aperture controls the size of the sweet spot of focus. Brighter apertures produce a smaller sweet spot of focus with more dramatic blur and darker apertures give you a larger area of focus with less blur. Sweet 50 Optic is part of the Lensbaby Optic SwapTM System. Composer Pro II with Sweet 50 Optic Product Specs: Focal Length: 50mm Aperture range from f/2.5 through f/22 12-blade internal aperture, controlled by a ring on the front of the optic Curved field of focus optic (creates a spot of focus surrounded by blur) Minimum focusing distance: 15” Maximum focusing distance: Infinity Focus Type: Manual Tilts from zero to 15 degrees Compatible with the Lensbaby Optic SwapTM System 2 multi-coated glass elements in one group 46mm front threads Composer Pro II with Sweet 50 Optic Box Contents: Composer Pro II Sweet 50 Optic Front and rear lens caps Microfiber bag Microfiber lens cloth User guides