The Zeiss Milvus 21mm f/2.8 ZE is a prime lens designed for full-frame Canon EF mount DSLRs, and can also be used with APS-C models where it will provide a 33.6mm equivalent focal length. The bright f/2.8 maximum aperture benefits working in varying lighting conditions and also offers increased control over depth of field. It uses the Distagon optical design to produce sharp imagery, even when working at the maximum aperture, and a floating elements system works to control chromatic aberrations and distortions. A Zeiss T* anti-reflective coating has also been applied to significantly reduce ghosting and lens flare for improved contrast and colour. It is a manual focus lens, and features a rubberized focus ring for precise focus control. Use the laser-engraved focusing and depth of field scales, along with an IR position dot and hard stops at both infinity and minimum focusing positions for easy focusing. All Milvus-series lenses feature a durable frosted, anodized metal lens barrel surface along with a weather-sealed construction with internal seals to protect against dust and moisture.