High-performance 50mm prime lens featuring a large F1.4 maximum aperture with outstanding contrast and resolution that are hallmarks of the Zeiss brand. The bright F1.4 maximum aperture offers excellent low light performance and adds to the 11-blade aperture and aspheric elements for gorgeous bokeh. 12 Elements in 9 Groups with two aspherical elements, including a high-precision Aa (advanced aspherical) type and Ed (Extra-low Dispersion) glass element, help maintain outstanding contrast and resolution right out to the image periphery. Zeiss T coating delivers superior contrast and resolution. 50mm wide aperture Prime lens with Zeiss Planar design Center to corner sharpness with outstanding resolution Bright F1.4 maximum aperture with excellent low light performance 12 Elements in 9 Groups with Advanced Aspheric and Ed glass Zeiss T coating delivers superior contrast and resolution 11-blade aperture and aspheric elements for gorgeous bokeh Ring Drive Ssm for fast, quiet and precise focusing Aperture ring with a selectable click On/Off switch Af/Mf switch for direct auto/manual focus control Dust and moisture resistant for robust reliability 50mm wide aperture Prime lens with Zeiss Planar design High-performance 'normal' 50mm prime lens is the ideal focal length for most photographers. The bright F1.4 maximum aperture delivers excellent low-light performance and control over defocused backgrounds. A state-of-the-art optical design includes 12 Elements in 9 Groups with Advanced Aspheric and Ed glass - reducing spherical aberration and distortion to an absolute minimum for a flat image plane that is consistent with the Planar name. Center to corner sharpness with outstanding resolution 12 Elements in 9 Groups including Aspherical lens design which dramatically reduces spherical aberration while also reducing lens size and weight. Spherical aberration is a slight misalignment of the light rays projected on the image plane. This is caused by differences in refraction at different points on conventional spherical lenses which degrade image quality in large-aperture lenses. Specially shaped ""aspherical"" elements near the diaphragm restore alignment of light rays at the image plane, maintaining high sharpness and contrast even at maximum aperture and can also be used at other points in the optical path to reduce distortion. While Ed glass dramatically reduces chromatic aberration and provides superior contrast across the entire image, even at large aperture settings. Zeiss T coating delivers superior contrast and resolution Coated optics were pioneered by Carl Zeiss - and this superb lens features the Zeiss T (T-Star) coating that virtually eliminates lens flare, internal reflection and light scattering that can otherwise occur at glass-to-air surfaces. The T coating contributes to outstanding image quality, with high contrast and uniformly excellent resolution right out to the image edges. Not simply applied to any lens - the T symbol only appears on multi-element lenses in which the required performance has been achieved throughout the entire optical path, therefore guaranteeing the highest quality. 11-blade circular aperture for gorgeous bokeh When changing your aperture to defocus the background, the light sources appear blurred. This 'bokeh' effect of the blurred background can be enhanced with circular aperture blades used in this lens.