The Rokinon 50mm T1.5 Cine DS Lens for Canon EF Mount is a fast manual focus prime lens. It provides a very fast maximum aperture of T1.5 for effective low light capture and shallow depth of field control and an 8 blade iris for attractive bokeh. Optimized for cinema and video applications, the focus and aperture control rings are outfitted with industry standard gearing, which provides an interface for working with a traditional follow focus. The aperture control ring has also been de-clicked, which enables smooth iris pulls. In addition, bright aperture and distance markings are printed on the lens barrel facing laterally to facilitate easier control by a focus puller.The 50mm has a minimum focus distance of 1.5'. Internal focusing minimizes the effects of lens breathing, which insures a more consistent angle-of-view when adjusting focus. The lens is composed of 9 elements in 6 groups, including one aspherical element and one hybrid aspherical element to reduce aberrations. In addition, a lens multi-coating helps to improve light transmission reducing flare and ghosting. The filter thread diameter is 77mm.With this 50mm lens, Rokinon introduces the DS series of cinema lenses, unifying their cine lenses in more than just name. Each of the DS branded lenses will offer the same alignment of their geared focus and aperture rings so that follow focus and other rig accessories won't need re-adjustment when swapping lenses. Also, each DS lens is tested to be color