Carl zeiss opton T sonnar 135mm 4.0 Optical design Focal length : 135mmSpeed : F/4~22Maximum format : 35mm full frameMount : Contax Outer mountDiagonal angle of view : 18.2° (35mm full frame) Lens construction : 4 elements in 3 groups Diaphragm mechanism: Diaphragm type : Manual Aperture control : Aperture ring Number of blades : 12 Focusing:Coupled to the rangefinder : Yes Closest focusing d..