Carl Zeiss T* ZM-mount lenses are specifically designed to minimize focus shift with aperture changes an important innovation with big benefits for rangefinder photography. As a result, you can expect improved accuracy of the rangefinder-defined focus. While the precise 10-blade aperture with 1/3 stop interval click stops ensures exact exposure. For reliable performance, Carl Zeiss T* ZM-mount lenses are designed with a wear resistant filter mount and an extremely accurate rangefinder coupling mechanism. FEATURES: The Carl Zeiss range of T* ZM-mount lenses offers the highest possible standards in terms of performance, reliability and, of course, image quality. Virtually zero geometric distortion for accurate reproduction of object shapes, particularly products and architecture Reduces unintended focus shift with aperture variation for improved accuracy of rangefinder defined focus Precise 10-blade aperture with 1/3 stop interval click stops ensures exact exposure Wear resistant filter mount for long-term reliability in tough conditions Highly advanced flare control that ensures crisp, brilliant images Extremely accurate rangefinder coupling mechanism ensures optical precision, contributing to superior image quality