Overview

The Canon Serenar 100mm f/4 I is a compact, brass-constructed lens with a 3-element design. Optically, it is sharp but exhibits slight vignetting wide open, which clears by f/8. Build quality is excellent, with smooth aperture and focus rings, though the coupled aperture/focus ring can hinder precise adjustment. It suits vintage rangefinder enthusiasts and mirrorless users seeking a lightweight telephoto, but its modest performance may disappoint those expecting modern sharpness.