Wide Angle Attachment... Designed to extend the wide angle readings of the Viewfinder. The Mark V Wide Angle Attachment is especially designed and manufactured for use with the Mark V and Mark Vb Director's Viewfinders. The combination of the attachment and the Viewfinder, will provide added wide angle range. 16mm cinematography, the field will be the same as a 5.5mm lens. Super 16mm, the field overview will be that of a 6mm lens. 35mm cinematography, the field will be that of a 10mm lens. 35mm anamorphic cinematography, field will be that of a 20mm lens. 2/3" video, the field will be that of a 5mm lens. 1/2" video, the field will be that of a 3.5mm lens. 6 Glass Elements: produces the sharpest image possible. Color Coding: Film sizes and video formats are color-coded for quick reading