The Samyang 85mm f1.5 AS IF UMC VDSLR Lens Samsung NX Fit is a fast, medium telephoto lens designed for shooting high-quality video footage on a full-frame and APS-C sensor, as well as professional camcorders. The gearing on the focus and aperture rings allow you to follow focus and provide you with aperture control from a professional camera rig. The aperture ring has also been de-clicked, which enables smooth iris pulls. The focal distance and aperture settings are clearly marked on the side of the lens barrel to ensure easy reference when mounted on a tripod. The large f1.5 aperture enables you to capture sharp images in low-light situations and also gives a beautifully blurred background. UMC stands for Ultra Multi Coated, which indicates that the lens has been covered with multi-layered, anti-reflective coating which minimises reflections and increases image contrast. Internal Focusing (IF) means that all focusing occurs within the lens, i.e. the lens will not change size as it zooms. Manual focus only.