A uniquely versatile super-wide lens, the Tri-Elmar-M 16-18-21mm f/4 ASPH. from Leica allows you to work with three separate focal lengths within one lens. The optical design, which includes a pair of aspherical elements, notably reduces distortion for clean, accurate rendering of interior and architectural subjects, and the aspherical elements also promote a more compact form factor. Seamless switching between 16mm, 18mm, and 21mm focal length positions is possible while retaining a minimum focusing distance of 1.6', and a floating elements design is used to maintain image quality even at close range.