Overview

The SMC Pentax-M 135mm f/3.5 is a compact, lightweight (around 290g) manual-focus telephoto from the late 1970s, featuring all-metal build and SMC coatings for good contrast. Optically, it uses a 5-elements, 5-groups formula and is usable wide open at f/3.5, with clear improvement by f/4 and excellent performance from f/5.6 to f/16. It may lag behind faster siblings at f/4 but holds its own stopped down. The lens suits portrait, travel, and black-and-white film shooters, and remains affordable and adaptable to modern mirrorless mounts.