The samyang 20mm f18 ed as umc is a wide angle manual focus lenses for dslr cameras having full frame sensor size the flow of light is devised based on the uniqueness of the distance from glass to sensor in mirrorless cameras to create optimal performance the bright f18 aperture assures fastest shutter speeds even under restricted lighting conditions to offer best quality images it can brighten up your everyday snapshots but it also creates an outstanding out of focus look by highlight