Zeiss Wide Angle 25mm f/2.8 Biogon T* ZM Manual Focus Lens for Zeiss Ikon and... 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