The 135mm f/2 Apo Sonnar T* ZE Lens for Canon EF Mount from Zeiss is medium telephoto lens that offers a wide maximum aperture, vibrant color rendition and attractive out-of-focus background. It maximum aperture of f/2 provides substantial light gathering for sharp, high resolution imaging and lovely shallow depth of field photography. A nine-blade circular aperture will offer harmonious background blur when shooting with minimal depth of focus. Special anomalous partial dispersion glass minimizes chromatic aberrations in this apochromat lens and anti-reflective coating reduces reflections and ghosting. It is a compact lens for its focal length and its "floating elements" optical design consists of 11 lens elements in 8 groups with minimal glass-to-air surfaces. The lens design ensures consistent imaging performance throughout the entire focusing range as well as sharpness to the periphery of the image. A rotation angle of 268Âº enables precise manual focusing and its all-metal barrel provides longevity and protection for its high-quality design.