Zeiss Planar T Manual Focus 85mm f/1.4 ZE Telephoto Lens for Canon EOS Cameras The lens' shallow depth of field at wide apertures allows the use of selective focus. This helps to emphasize the primary subject by defocusing the background. The 9-blade, circular aperture produces a smooth and natural rendition of defocused images, as well as nearly circular shapes of point sources of light. Geometrical distortion is imperceptibly low, allowing high quality documentation photographs, both analog and digital.