The 21mm f/1.8 Ultron M-Mount Lens from Voigtlander is a manual focus wide-angle prime lens with a maximum aperture of f/1.8 making it ideal for shallow depth of field photography and effective with fast shutter speeds in low light. Its optical design consists of 13 elements in 11 groups including an aspherical lens element to correct aberrations. Ten aperture blades help to create beautiful bokeh when shooting with a shallow focus and its smooth manual focus action offers precise focusing. An all-metal barrel provides longevity and a built-in lens hood deflects stray light from entering the lens and offers a degree of protection for the lens as well.