Overview

The Leica Tri-Elmar-M 16-18-21mm f/4 ASPH offers three ultrawide focal lengths in a compact, all-metal build with precision controls. Optically, it delivers excellent contrast and sharpness at normal viewing sizes, with well-controlled distortion (0.13-0.33% barrel) and good light falloff correction. However, under high magnification, resolving power is not exceptional compared to newer Leica primes. The f/4 maximum aperture makes it slow in low light, and close-focus magnification is limited. It requires an external viewfinder for accurate framing. Best suited for Leica M8/M9 owners seeking a versatile ultrawide solution.