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 Swap System.